'--subscription' sometimes exists sometimes not

[daxianji007]

Related command
az account alias xxx
az webapp xxx

Describe the bug
I am using the python code to get all the help information of commands. I find that a global parameter '--subscription' sometimes exists sometimes not. This happens in (all?) commands from extension 'account' and 'webapp'.

To Reproduce
Install azure-cli and extension 'account', run the following python code. Code is easy. It loads all the commands and see if commands 'az account alias create' has parameter '--subscription' and run it 10 times.

from azure.cli.core import MainCommandsLoader, AzCli
from azure.cli.core.commands import AzCliCommandInvoker
from azure.cli.core.parser import AzCliCommandParser
from azure.cli.core.file_util import create_invoker_and_load_cmds_and_args, get_all_help
from azure.cli.core._help import AzCliHelp

for i in range(10):    
    az_cli = AzCli(cli_name='az',
            commands_loader_cls=MainCommandsLoader,
            invocation_cls=AzCliCommandInvoker,
            parser_cls=AzCliCommandParser,
            help_cls=AzCliHelp)
    create_invoker_and_load_cmds_and_args(az_cli)
    help_files = get_all_help(az_cli)
    command_alias_create = next((h for h in help_files if h.command == 'account alias create'), None)
    print(f"[Note] 'account alias create' has {len(command_alias_create.parameters)} parameters")
    print(f"[Note] 'account alias create' contains '--subscription': {'--subscription' in (p.name for p in command_alias_create.parameters)}")

This is the output in my side. Sometimes command 'az account alias create' has 14 parameters with '--subscription', sometimes it has 13 parameters without '--subscription'.

Expected behavior
The output should always be the same (always has '--subscription' or not).

Environment summary

Python 3.9.7
{
  "azure-cli": "2.35.0",
  "azure-cli-core": "2.35.0",
  "azure-cli-telemetry": "1.0.6",
  "extensions": {
    "account": "0.2.2",
    "acrtransfer": "1.1.0",
    "ad": "0.1.0",
    "aem": "0.3.0",
    "ai-examples": "0.2.5",
    "aks-preview": "0.5.63",
    "alertsmanagement": "0.2.2",
    "alias": "0.5.2",
    "amg": "0.1.0",
    "application-insights": "0.1.16",
    "appservice-kube": "0.1.6",
    "arcappliance": "0.2.18",
    "arcdata": "1.3.1",
    "attestation": "0.2.0",
    "authV2": "0.1.1",
    "automation": "0.1.1",
    "azure-batch-cli-extensions": "6.0.0",
    "azure-cli-ml": "1.37.0",
    "azure-devops": "0.25.0",
    "azure-firewall": "0.13.0",
    "azure-iot": "0.14.0",
    "azurestackhci": "0.2.3",
    "baremetal-infrastructure": "1.0.0",
    "blockchain": "0.1.1",
    "blueprint": "0.3.1",
    "cli-translator": "0.3.0",
    "cloud-service": "0.2.0",
    "communication": "1.1.0",
    "confidentialledger": "0.1.0",
    "confluent": "0.4.0",
    "connectedk8s": "1.2.8",
    "connectedmachine": "0.4.1",
    "connectedvmware": "0.1.6",
    "containerapp": "0.3.1",
    "cosmosdb-preview": "0.15.0",
    "costmanagement": "0.2.1",
    "csvmware": "0.3.0",
    "custom-providers": "0.2.1",
    "customlocation": "0.1.3",
    "databox": "0.1.3",
    "databricks": "0.8.0",
    "datadog": "0.1.1",
    "datafactory": "0.5.0",
    "datamigration": "0.3.0",
    "dataprotection": "0.3.0",
    "datashare": "0.2.0",
    "db-up": "0.2.7",
    "deploy-to-azure": "0.2.0",
    "desktopvirtualization": "0.2.0",
    "dev-spaces": "1.0.6",
    "diskpool": "0.2.0",
    "dms-preview": "0.15.0",
    "dnc": "0.1.3",
    "edgeorder": "0.1.0",
    "elastic": "0.1.0",
    "enterprise-edge": "0.1.1",
    "eventgrid": "0.4.9",
    "express-route-cross-connection": "0.1.1",
    "footprint": "1.0.0",
    "front-door": "1.0.16",
    "functionapp": "0.1.1",
    "fzf": "1.0.2",
    "guestconfig": "0.1.1",
    "hack": "0.4.3",
    "hardware-security-modules": "0.1.0",
    "healthbot": "0.1.0",
    "healthcareapis": "0.3.4",
    "hpc-cache": "0.1.5",
    "image-copy-extension": "0.2.9",
    "image-gallery": "0.1.3",
    "import-export": "0.1.1",
    "init": "0.1.0",
    "interactive": "0.4.5",
    "internet-analyzer": "0.1.0rc6",
    "ip-group": "0.1.2",
    "k8s-configuration": "1.5.1",
    "k8s-extension": "1.2.0",
    "k8sconfiguration": "0.2.4",
    "kusto": "0.5.0",
    "log-analytics": "0.2.2",
    "log-analytics-solution": "0.1.1",
    "logic": "0.1.5",
    "logz": "0.1.0",
    "maintenance": "1.3.0",
    "managementpartner": "0.1.3",
    "mesh": "0.10.7",
    "mixed-reality": "0.0.4",
    "ml": "2.2.3",
    "monitor-control-service": "0.3.0",
    "netappfiles-preview": "0.3.2",
    "next": "0.1.2",
    "notification-hub": "0.2.0",
    "offazure": "0.1.0",
    "peering": "0.2.1",
    "portal": "0.1.2",
    "providerhub": "0.2.0",
    "purview": "0.1.0",
    "quantum": "0.15.0",
    "quota": "0.1.0",
    "rdbms-connect": "1.0.2",
    "redisenterprise": "0.1.1",
    "resource-graph": "2.1.0",
    "resource-mover": "0.1.1",
    "sap-hana": "0.6.5",
    "scheduled-query": "0.5.0",
    "scvmm": "0.1.4",
    "sentinel": "0.1.2",
    "serial-console": "0.1.1",
    "spring-cloud": "3.1.3",
    "ssh": "1.1.1",
    "stack-hci": "0.1.4",
    "storage-blob-preview": "0.6.1",
    "storage-preview": "0.8.2",
    "storagesync": "0.1.2",
    "stream-analytics": "0.1.2",
    "subscription": "0.1.4",
    "support": "1.0.3",
    "timeseriesinsights": "0.2.1",
    "virtual-network-manager": "0.5.0",
    "virtual-network-tap": "0.1.0",
    "virtual-wan": "0.2.11",
    "vm-repair": "0.4.3",
    "vmware": "4.0.2",
    "webapp": "0.4.0",
    "webpubsub": "1.1.0"
  }
}

Additional context
I am using this information to generate the Docs Page(https://docs.microsoft.com/en-us/cli/azure/account/alias?view=azure-cli-latest) . Currently I have to hard-code the global parameters for all commands because of this issue.

[yonzhan]

@zhoxing for awareness