Remove CMP0135 policy checks.

[bdice]

Description

CMP0135 changed behavior in CMake 3.24. Now that we require CMake 3.30.4+, we don't need to be concerned about old versions of the policy. https://cmake.org/cmake/help/latest/policy/CMP0135.html

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

[bdice]

/merge