ci: Increase timeout iOS 26 unit tests

[github-actions]

Note

The pull request "ci: Increase timeout iOS 26 unit tests" was created by @philipphofmann but did not reference an issue. Therefore this issue was created for better visibility in external tools like Linear.

Increased the timeout to 40 minutes because just building the tests often takes 20 minutes.

#skip-changelog

[linear]

COCOA-896