cleanup: use Status factory functions

[alevenberg]

#14107

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This change is 

[codecov]

Codecov Report

Attention: Patch coverage is 67.77778% with 29 lines in your changes are missing coverage. Please review.

Project coverage is 93.79%. Comparing base (bd6390c) to head (cb78c1f).
Report is 7 commits behind head on main.

Files	Patch %	Lines
google/cloud/internal/openssl/sign_using_sha256.cc	14.28%	24 Missing ⚠️
...internal/openssl/parse_service_account_p12_file.cc	33.33%	4 Missing ⚠️
...cloud/internal/grpc_impersonate_service_account.cc	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #14221      +/-   ##
==========================================
+ Coverage   93.24%   93.79%   +0.54%     
==========================================
  Files        2206     2293      +87     
  Lines      192142   202934   +10792     
==========================================
+ Hits       179156   190332   +11176     
+ Misses      12986    12602     -384     

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