Adds logic to check for pcw_ignore flag

[linguini-dev]

This PR adds logic that allows us to prevent PCW from deleting disks in Google Cloud if the flag pcw_ignore is configured.

Related ticket: https://progress.opensuse.org/issues/174220

Test run logs:

2025-01-29 17:26:16,560 ocw.lib.gce  DEBUG    [namespace] Searching for disks in europe-west1-b
2025-01-29 17:26:16,725 ocw.lib.gce  DEBUG    [namespace] 1 disks found
2025-01-29 17:26:16,789 ocw.lib.gce  DEBUG    [namespace] Ignoring testing-pcw-ignore due to 'pcw_ignore' label set to '1'

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 79.60%. Comparing base (7dfb385) to head (d871823).
Report is 13 commits behind head on master.

Files with missing lines	Patch %	Lines
ocw/lib/gce.py	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #423      +/-   ##
==========================================
- Coverage   79.61%   79.60%   -0.01%     
==========================================
  Files          21       21              
  Lines        1628     1632       +4     
==========================================
+ Hits         1296     1299       +3     
- Misses        332      333       +1     

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