chore(metrics): Clean up metrics CLI docs

[vgrozdanic]

Metrics have been deprecated since October 7th 2024, so this is no longer valid, and we should remove instructions on how to send metrics, because this doesn't even work.

This PR getsentry/sentry-cli#2710 will clean up metrics commands in CLI, but this can be cleaned up separately.

[vercel]

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Project	Deployment	Preview	Comments	Updated (UTC)
develop-docs	✅ Ready	Preview	Comment	Aug 14, 2025 9:48am
sentry-docs	✅ Ready	Preview	Comment	Aug 14, 2025 9:48am

[cleptric]

Have a look at #14602, as we should add a redirect so it does not 404. (In the very unlikely case someone bookmarked this specific page, etc.)

[codecov]

Bundle Report

Changes will increase total bundle size by 3.44kB (0.02%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
sentry-docs-edge-server-array-push	351.74kB	45 bytes (0.01%) ⬆️
sentry-docs-client-array-push	9.9MB	-6 bytes (-0.0%) ⬇️
sentry-docs-server-cjs	12.45MB	3.4kB (0.03%) ⬆️

Affected Assets, Files, and Routes:

view changes for bundle: sentry-docs-edge-server-array-push

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
src/middleware.js	45 bytes	207.02kB	0.02%

view changes for bundle: sentry-docs-client-array-push

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
static/chunks/pages/_app-*.js	-3 bytes	882.71kB	-0.0%
static/chunks/8321-*.js	-3 bytes	425.87kB	-0.0%
static/k_tz3mlfxvGchrQERT1bL/_buildManifest.js (New)	684 bytes	684 bytes	100.0% 🚀
static/k_tz3mlfxvGchrQERT1bL/_ssgManifest.js (New)	77 bytes	77 bytes	100.0% 🚀
static/UPa4nSeCGqlARlg0okHZ-*.js (Deleted)	-77 bytes	0 bytes	-100.0% 🗑️
static/UPa4nSeCGqlARlg0okHZ-*.js (Deleted)	-684 bytes	0 bytes	-100.0% 🗑️

view changes for bundle: sentry-docs-server-cjs

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
1729.js	-1 bytes	1.78MB	-0.0%
../instrumentation.js	-5 bytes	1.1MB	-0.0%
9523.js	-3 bytes	1.08MB	-0.0%
../app/[[...path]]/page.js.nft.json	1.14kB	754.18kB	0.15%
../app/platform-redirect/page.js.nft.json	1.14kB	754.1kB	0.15%
../app/sitemap.xml/route.js.nft.json	1.14kB	751.57kB	0.15%