ci: disable datacatalog quickstart as service is deprecated

[scotthart]

The deprecated datacatalog service is denying RPCs to its endpoint. This PR disables the quickstart to get CI passing. The library for the deprecated service will be removed in a future PR, tracked by #16165.

[gemini-code-assist]

Code Review

This pull request removes the integration test configuration and properties for the datacatalog_quickstart target from the CMakeLists.txt file in google/cloud/datacatalog. There are no review comments, and I have no feedback to provide.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.20%. Comparing base (ce5aa34) to head (c874e78).

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16166      +/-   ##
==========================================
- Coverage   92.20%   92.20%   -0.01%     
==========================================
  Files        2264     2264              
  Lines      209092   209092              
==========================================
- Hits       192802   192783      -19     
- Misses      16290    16309      +19     

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