browser-integration-tests: port browserTracingIntegration suites to span streaming #24142

Follow the porting recipe in the parent issue.

Biggest single group in this package: 50 pinned files across suites/tracing/browserTracingIntegration/*, 27 of which assert on transaction envelopes.

Pageload and navigation span names are low cardinality under streaming, so the name assertions change everywhere, not just the helper.

Twins to fold back

14 subdirectories already have a -streamed twin next to the static original:

pageload, navigation, backgroundtab-pageload, linked-traces, http-timings, reportPageLoaded, spotlight-interaction-filter, long-tasks-enabled, long-tasks-disabled, long-tasks-before-navigation, long-tasks-and-animation-frame-enabled, long-animation-frame-enabled, long-animation-frame-disabled, long-animation-frame-before-navigation.

Delete the static original and rename the twin to the base name. Do not keep both.