set an exception for migrate file permissions

[grokspawn]

Description of the change:
Reverts #1524 changes to alpha/declcfg/write.go associated with FBC migration support.

Motivation for the change:
Though this represents a legitimate ratcheting of security concerns, and we'd like to in general adhere to the security best practices of gosec linter, in this case we intend to rely on appropriate umask configuration of end users.
Not only were users of the binary impacted, but indirect clients who vendored the packages.

Reviewer Checklist

• Implementation matches the proposed design, or proposal is updated to match implementation
• Sufficient unit test coverage
• Sufficient end-to-end test coverage
• Docs updated or added to /docs
• Commit messages sensible and descriptive

[openshift-ci]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 55.27%. Comparing base (0ec1210) to head (ae28a6b).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
alpha/declcfg/write.go	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1798   +/-   ##
=======================================
  Coverage   55.27%   55.27%           
=======================================
  Files         136      136           
  Lines       15976    15976           
=======================================
  Hits         8830     8830           
  Misses       5991     5991           
  Partials     1155     1155           

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[grokspawn]

/approve

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: acornett21, grokspawn

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[grokspawn]

/hold remodel description to capture more context