Remove the cache based link resolver

[d-ronnqvist]

Bug/issue #, if applicable:

Summary

This removes the cache based link resolver in favor of the (default) hierarchy based link resolver.

It also cleans up a few small pieces in the documentation context that dealt with behavior specific to the cache based link resolver that are now unused.

Note:
This change is only intended for the "main" branch. The cache based link resolver should remain an opt-in alternative in the 5.9 release.

Dependencies

None

Testing

Nothing specific to test. The hierarchy based link resolver was already the default and everything should continue to behave the same as before.

Checklist

Make sure you check off the following items. If they cannot be completed, provide a reason.

• [ ] Added tests
• Ran the ./bin/test script and it succeeded
• Updated documentation if necessary

[d-ronnqvist]

@swift-ci please test

[Kyle-Ye]

Amazing clean up 👍

[d-ronnqvist]

@swift-ci please test

[d-ronnqvist]

@swift-ci please test