Add UI tests for commit signature badges
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## Why are we doing this work
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A brief explanation of the why, not the what or how. Assume the reader doesn't know the
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The commit signature badges are rendered via several HAML templates in https://gitlab.com/gitlab-org/gitlab/-/tree/3f56fd6515ae57f91c5b7619381a14f84c3843c0/app/views/projects/commit.
Currently, we do not have any tests for these. We should add tests for all signatures types and also all signature verification states.
The test bootstrapping for signatures is also non-trivial, so this may be a good opportunity to add some shared-contexts for these.
## Relevant links
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## Non-functional requirements
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- [ ] Documentation:
- [ ] Feature flag:
- [ ] Performance:
- [ ] Testing:
## Implementation plan
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Add tests for the signature badge to spec/views/projects/commit/show.html.haml_spec.rb.
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## Verification steps
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issue