Remove deprecated support for CUDA 11

[bdice]

Description

This PR removes deprecated support for CUDA 11 architecture selection.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.
• The cmake-format.json is up to date with these changes.
• I have added new files under rapids-cmake/
  • I have added include guards (include_guard(GLOBAL))
  • I have added the associated docs/ rst file and update the api.rst

[robertmaynard]

@bdice Can you either merge 914 into this, or create a new PR that tests both together? We would should validate that combined together all the tests are passing.

[bdice]

Yes, this needed #914 to pass. Now that that PR is merged, I'll update this one.

[bdice]

/merge