ci: skip workflows on documentation-only changes

[Kiran01bm]

Summary

• Add paths-ignore filters to GitHub Actions workflows to skip CI runs when only documentation files are changed
• This reduces unnecessary CI load and resource usage for documentation updates

Changes

Updated all test and lint workflows to ignore:

• All Markdown files (**/*.md)
• The docs/ directory

Workflows Updated

• buildandrun-docker.yml
• linter.yml (golangci-lint only checks Go code)
• mysql8-docker.yml
• mysql8.0.28-docker.yml
• mysql8.0.42-docker.yml
• mysql84-docker.yml
• mysql8_rbr_minimal-docker.yml
• mysql96-docker.yml

Workflows Not Updated

• release.yml - intentionally left unchanged as it only triggers on version tags