feat(performance): Updates Web Vitals issue detection to consolidate lcp, fcp, and ttfb into a single issue

[edwardgou-sentry]

LCP, FCP, and TTFB issues often share similar root causes and fixes when analyzed by Seer. To reduce duplicate similar issues, updates Web Vitals issue detection to consolidate low LCP, FCP, and TTFB scores into a single rendering grouping/fingerprint.

• Slightly changes issue event tags to support this. Each web vital score and value is stored as its own tag on the issue event.
• The trace sample for the event is the p75 sample chosen from the worst scoring vital.
• Slight change to title and subtitle generation (this will likely be replaced in a separate pr for further title improvement)

[codecov]

❌ 1 Tests Failed:

Tests completed	Failed	Passed	Skipped
29666	1	29665	243

View the top 1 failed test(s) by shortest run time

tests.sentry.tasks.test_web_vitals_issue_detection.WebVitalsIssueDetectionDataTest::test_run_detection_groups_rendering_vitals

Stack Traces | 5.28s run time

#x1B[1m#x1B[.../sentry/tasks/test_web_vitals_issue_detection.py#x1B[0m:336: in test_run_detection_groups_rendering_vitals
    assert lcp_occurrence.issue_title == "Rendering score needs improvement"
#x1B[1m#x1B[31mE   AssertionError: assert 'Render time ...d improvement' == 'Rendering sc...s improvement'#x1B[0m
#x1B[1m#x1B[31mE     #x1B[0m
#x1B[1m#x1B[31mE     - Rendering score needs improvement#x1B[0m
#x1B[1m#x1B[31mE     ?        ^^           -#x1B[0m
#x1B[1m#x1B[31mE     + Render time Web Vital scores need improvement#x1B[0m
#x1B[1m#x1B[31mE     ?       ++ ^^^^^^^^^^^^      +#x1B[0m

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