Replace usages of assertFileOccurences by comparisons with golden files (1/n)

[smelc]

Changelog

- description: |
    Replace usages of assertFileOccurences by comparisons with golden files
# uncomment types applicable to the change:
  type:
  # - feature        # introduces a new feature
  # - breaking       # the API has changed in a breaking way
  # - compatible     # the API has changed but is non-breaking
  # - optimisation   # measurable performance improvements
  # - improvement    # QoL changes e.g. refactoring
  # - bugfix         # fixes a defect
  - test           # fixes/modifies tests
  # - maintenance    # not directly related to the code
  # - release        # related to a new release preparation
  # - documentation  # change in code docs, haddocks...

Context

• Contributes to fixing assertFileOccurences doesn't check CBOR payload #415
• There will be more PRs like this, but I rather do multiple small PRs than a big one.

How to trust this PR

Highlight important bits of the PR that will make the review faster. If there are commands the reviewer can run to observe the new behavior, describe them.

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. See Running tests for more details
• Self-reviewed the diff

[smelc]

This can be removed, because we actually do a nearly-full (only the cbor Hex gets ignored) comparison against a golden file.

[smelc]

I could have put more in this PR, but since I'm off tomorrow (Friday), let's try to merge it sooner than later.

[Jimbo4350]

👍