CI: Move Mermaid check into doc markdown lint job
What does this MR do and why?
The CI job static-analysis did not pick up doc/ changes and linting mermaid in markdown also makes more sense in a doc related CI job.
Follow-up of gitlab-org/quality/engineering-productivity/master-broken-incidents#5322 (comment 1781356888) and !144328 (comment 1781423756).
Refs #441248 (closed)
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Edited by Peter Leitzen