Move certain MacOS 12 tests to run on newer MacOS 14 boxes

[Cawllec]

Goal

Moves steps previously running on MacOS 12 to run on MacOS 14. This will allow us to decommission older MacOS boxes from our test infrastructure over time.

Most of the RN iOS build steps (pre-0.73) have not been moved, as they currently fail to run successfully on MacOS 14. These have been ticketed as a separate issue.

[github-actions[bot]]

@bugsnag/browser bundle size diff

	Minified	Minfied + Gzipped
Before	43.80 kB	13.43 kB
After	43.80 kB	13.43 kB
±	No change	No change

code coverage diff

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