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

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.