[mermaid] Parse error in search results

If you search for something on GitLab, a preview is shown for each result. GitLab tries to render mermaid charts in these previews even if it does not contain the complete chart. Therefore an ugly error message is shown that the mermaid module was unable to parse the chart.

STR:

1. Create an issue that starts with a mermaid chart within the first 200 characters or so, but make sure that the end of the chart is not in this range
2. Search for that issue
3. Can't load mermaid module: Error: Parse error on line...

Live example: https://gitlab.com/search?project_id=13083&scope=merge_requests&search=%60%60%60mermaid

added devopsplan markdown typebug labels

We should probably disable rendering of Mermaid diagrams in the search results.

Setting groupproject management based on markdown.

added groupproject management label

mentioned in issue #36571 (closed)

added frontend label

mentioned in issue #37186 (closed)

changed milestone to %12.7

added priority3 severity3 labels

changed weight to 1

added [deprecated] Accepting merge requests label

mentioned in merge request !23033 (merged)

changed milestone to %12.8

added missed:12.7 label

closed via merge request !23033 (merged)

mentioned in commit ea9ee18c

mentioned in commit 69025cdc

added Category:Markdown label

added sectiondev label