test(Angular): fix `angularInit()` tests on Safari v15+

Previously, the `angularInit()` tests assumed that the Safari browser
uses the `safari-extension:` protocol for browser extension URLs. This
is true for versions <15. However, since v15, Safari on iOS only
recognizes the `chrome-extension:` protocol, which causes the tests to
fail ([example failure][1]).

This commit updates the tests to use the correct protocol according to
the version of Safari used.

NOTE:
On macOS, Safari v15+ recognizes both `safari-extension:` and
`chrome-extension:`, so it is OK to always use the later with Safari
v15+ (regardless of the platform).

[1]: https://circleci.com/gh/angular/angular.js/3527

Co-authored-by: George Kalpakas <kalpakas.g@gmail.com>

Closes #17166