Make the option enablePreWarmedAppStartTracing stable.

Cancel in progress workflow runs when pushing new commits to a PR
to save CI computing time.

Fixes GH-3213

Split the UIKit and Application Init span into one span for UIKit Init
and another for Application Init. The UIKit Init span ends when the
users start the SentrySDK. We recommend that the SentrySDK is the first
to call in the UIApplication.didFinishLaunching method because
otherwise, users won't receive any potential crash reports for code
running before our SDK. Therefore, we pick the start time of our SDK as
when the UIApplicationDelegate.didFinishLaunching is called.

Fixes GH-3345

Set the up-tests environment when running UI tests in CI so that we can
apply filters in Sentry.

Send the complete list of debug meta for app start transactions so we
can calculate statistics on the number and size of libraries loaded on
the backend when the app starts.

Fixes GH-3541

Don't override sentry-trace and baggage headers in a http request.
Cross platform SDKs may set this headers and we're overriding it.

The teardown of the SentryFramesTracker didn't work properly in tests.
The clearTestState method continuously initialized a new frames tracker
cause it accessed the property dependency container. This is fixed now
by calling SentryFramesTracker.stop directly in
SentryDependencyContainer.reset which is also called in clearTestState.
Furthermore, the SentryFramesTracker.stop now resets all frames and
removes all observers.

* Remove dispatch queue metadata collection

* Hardcode "main" as the name of the main thread

* Format code

* Update CHANGELOG.md

* use thread wrapper main thread dispatch

---------

Co-authored-by: Sentry Github Bot <bot+github-bot@sentry.io>
Co-authored-by: Andrew McKnight <andrew.mcknight@sentry.io>