Add missing attribute filter tests

[Cali0707]

Fixes #7488

Proposed Changes

• Add unit tests for filters with missing attributes
• Add rekt test for filters with missing attributes

Pre-review Checklist

• At least 80% unit test coverage
• E2E tests for any new behavior
• Docs PR for any user-facing impact
• Spec PR for any new API feature
• Conformance test for any change to the spec

Release Note

Docs

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (31abcdb) 75.55% compared to head (63f508a) 75.55%.
Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7516   +/-   ##
=======================================
  Coverage   75.55%   75.55%           
=======================================
  Files         261      261           
  Lines       14667    14667           
=======================================
  Hits        11082    11082           
  Misses       3006     3006           
  Partials      579      579           

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[matzew]

/lgtm
/approve

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Cali0707, matzew

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