Stop scanning ee/spec for externalized strings

What does this MR do and why?

We currently scan ee/spec for externalized strings, which brings up a few false-positives. These false positives create an unnecessary burden for translators and increase our scan time quite a bit (about 19% of our rb/erb/haml files are found inside ee/spec). On my machine this reduces the execution time from 29.4s to 21.5s when running on one core only.

Fixed two specs which used confusing placeholder names in strings.

See: #28597 (closed)

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How to set up and validate locally

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MR acceptance checklist

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Related to #28597 (closed)