Suppressed binary authorization attestor key signature algorithm diffs if the algorithms are equivalent

[modular-magician]

Resolved #8511. Suppressed binary authorization attestor key signature algorithm diffs if the algorithms are equivalent; different ways of getting this key seem to provide different (but equivalent) results.

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Release Note Template for Downstream PRs (will be copied)

binaryauthorization: fixed permadiff in `google_binary_authorization_attestor`

Derived from GoogleCloudPlatform/magic-modules#4575

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