Parametrize pattern for importer user name removal in imported objects

What does this MR do and why?

Describe in detail what your merge request does and why.

Depending on source environment and user name of the token used, test needs to properly remove username mentions from imported comments and descriptions so it can be compared to source.

This adds ability to pass in pattern of user name

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.