core(lint): Add custom `no-focused-tests` and `no-skipped-tests` rules

[Lms24]

I noticed that it.skip and it.only usage is not correctly flagged in vitest files by our jest eslint plugin. To fix this, I initially wanted to add eslint-plugin-vitest but realized it requires Eslint 9 which we can't use (we're on eslint 7) because it requires Node 18 🙃

So instead, this PR adds two simple custom rules to ignore (it|test|describe).(skip|only). These rules now also flag vitest-based skip and only functions but led to duplications with the two rules from eslint-plugin-jest. So this PR also disables the jest versions in favour of the custom rules. To be clear, the custom rules are likely a bit less robust than the jest/vitest version but until we can use the actual vitest plugin, I think it's fine to stay with our custom version.

closes https://github.com/getsentry/sentry-javascript/issues/13429

[github-actions[bot]]

size-limit report 📦

⚠️ Warning: Base artifact is not the latest one, because the latest workflow run is not done yet. This may lead to incorrect results. Try to re-run all tests to get up to date results.

Path	Size	% Change	Change
@sentry/browser	22.52 KB	-	-
@sentry/browser (incl. Tracing)	34.85 KB	-	-
@sentry/browser (incl. Tracing, Replay)	71.27 KB	-	-
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags	64.54 KB	-	-
@sentry/browser (incl. Tracing, Replay with Canvas)	75.62 KB	-	-
@sentry/browser (incl. Tracing, Replay, Feedback)	88.35 KB	-	-
@sentry/browser (incl. Tracing, Replay, Feedback, metrics)	90.18 KB	-	-
@sentry/browser (incl. metrics)	26.83 KB	-	-
@sentry/browser (incl. Feedback)	39.59 KB	-	-
@sentry/browser (incl. sendFeedback)	27.18 KB	-	-
@sentry/browser (incl. FeedbackAsync)	31.9 KB	-	-
@sentry/react	25.28 KB	-	-
@sentry/react (incl. Tracing)	37.83 KB	-	-
@sentry/vue	26.66 KB	-	-
@sentry/vue (incl. Tracing)	36.68 KB	-	-
@sentry/svelte	22.65 KB	-	-
CDN Bundle	23.77 KB	-	-
CDN Bundle (incl. Tracing)	36.53 KB	-	-
CDN Bundle (incl. Tracing, Replay)	70.91 KB	-	-
CDN Bundle (incl. Tracing, Replay, Feedback)	76.22 KB	-	-
CDN Bundle - uncompressed	69.61 KB	-	-
CDN Bundle (incl. Tracing) - uncompressed	108.28 KB	-	-
CDN Bundle (incl. Tracing, Replay) - uncompressed	219.8 KB	-	-
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed	232.99 KB	-	-
@sentry/nextjs (client)	37.6 KB	-	-
@sentry/sveltekit (client)	35.44 KB	-	-
@sentry/node	115.91 KB	-	-
@sentry/node - without tracing	90.01 KB	-	-
@sentry/aws-serverless	99.45 KB	-	-

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