Use rspec-parameterized for table-based tests

What does this MR do?

Adds the rspec-parameterized gem, documents it, and converts a number of existing ad-hoc table-based tests to use the framework as a proof of concept.

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Why was this MR needed?

Action point from %9.4 retrospective

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Does this MR meet the acceptance criteria?

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Related to https://gitlab.com/gitlab-org/gitlab-ce/35804

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