test(bigquery): handle 404 err when cleaning stale datasets

[alvarowolfx]

When multiple CI steps run in parallel, there is a change of then trying to delete the same dataset (BigQuery metadata service has an eventual consistency model). This PR checks if the error when trying to fetch a Dataset is a 404 and skip it.

Fixes #3572

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.88%. Comparing base (5ac621b) to head (c33dd10).
⚠️ Report is 10 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3594      +/-   ##
==========================================
+ Coverage   95.76%   95.88%   +0.11%     
==========================================
  Files         125      125              
  Lines        5005     5029      +24     
==========================================
+ Hits         4793     4822      +29     
+ Misses        212      207       -5     

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