feat(reliability) Add flag to disable telegram notifications

[bplatak]

We want to run multiple redundant instances of pyth-observer which poses an interesting problem around coordinations and alert deduplication. With ZenDuty we get deduplication for free - we just send it a hash and it does the rest for us - but Telegram does not offer the same functionality.

Longer term we might need to run istio coordination layer (or just use some db 🤷 ) but for now we can at least get reliable zenduty alerts even if tg isn't there yet.

[Copilot]

Pull Request Overview

This PR adds a flag to disable Telegram notifications in the pyth-observer to support running multiple redundant instances with reliable ZenDuty alerts while avoiding duplicate Telegram messages.

• Adds a --disable-telegram CLI flag and environment variable option
• Modifies the dispatch logic to skip Telegram events when the flag is enabled
• Updates metrics to track whether Telegram notifications are enabled

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
pyth_observer/cli.py	Adds the new --disable-telegram CLI option and passes it to Observer
pyth_observer/init.py	Updates Observer constructor to accept and pass the disable_telegram parameter
pyth_observer/dispatch.py	Adds logic to skip TelegramEvent processing when disabled
pyth_observer/metrics.py	Adds telegram_enabled field to observer info metrics

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