docs: remove "mode" from db configuration

[MichaelScofield]

What's Changed in this PR

close #1712

Checklist

• Please confirm that all corresponding versions of the documents have been revised.
• Please ensure that the content in sidebars.ts matches the current document structure when you changed the document structure.
• This change requires follow-up update in localized docs.

[killme2008]

There are other files which contain this option:

~/Documents/greptime-docs/docs (main ✗) ag mode | grep "mode = " |grep stand
user-guide/protocols/http.md:123:mode = "standalone"
user-guide/deployments/configuration.md:625:mode = "standalone"
reference/telemetry.md:36:mode = "standalone"
~/Documents/greptime-docs/docs (main ✗) ag mode | grep "mode = " |grep distributed
user-guide/deployments/configuration.md:619:mode = "distributed"

[cloudflare-workers-and-pages]

Deploying greptime-docs with    Cloudflare Pages

Latest commit:	545fbc5
Status:	✅  Deploy successful!
Preview URL:	https://542c16be.greptime-docs.pages.dev
Branch Preview URL:	https://docsremove-mode-from-config.greptime-docs.pages.dev

View logs

[MichaelScofield]

There are other files which contain this option:

~/Documents/greptime-docs/docs (main ✗) ag mode | grep "mode = " |grep stand
user-guide/protocols/http.md:123:mode = "standalone"
user-guide/deployments/configuration.md:625:mode = "standalone"
reference/telemetry.md:36:mode = "standalone"
~/Documents/greptime-docs/docs (main ✗) ag mode | grep "mode = " |grep distributed
user-guide/deployments/configuration.md:619:mode = "distributed"

removed

[fengjiachun]

LGTM