Fix default PlatformType in GCP entrypoint

[joshbranham]

What does this PR do? / Related Issues / Jira

Fix a bug from the previous Platform work that defaulted GCP to the wrong Platform.

Checklist

• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have tested the functionality against gcp / aws, it doesn't cause any regression
• I have added execution results to the PR's readme

Reviewer's Checklist

• (This needs to be done after technical review) I've run the branch on my local, verified that the functionality is ok

How to test this PR locally / Special Instructions

Logs

[abyrne55]

Good catch @joshbranham!

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: abyrne55

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[openshift-ci]

@joshbranham: all tests passed!

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[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 25.79%. Comparing base (158ebb9) to head (fa2c1a9).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/verifier/gcp/entry_point.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #283   +/-   ##
=======================================
  Coverage   25.79%   25.79%           
=======================================
  Files          26       26           
  Lines        1845     1845           
=======================================
  Hits          476      476           
  Misses       1341     1341           
  Partials       28       28           

Files with missing lines	Coverage Δ
pkg/verifier/gcp/entry_point.go	0.00% <0.00%> (ø)