Remove bold text from NOTE alerts

In &5020 (closed), we decided to use only two alerts (note, warning), and eliminate any bold text coming after the icon.

This issue is about:

1. Getting rid of bold text **Note:**:

   for i in `grep -r "NOTE: \*\*Note:\*\*" doc | uniq | cut -d':' -f1`; do sed -i 's/NOTE: \*\*Note:\*\*/NOTE:/' $i; done

The above steps will need to be repeated for all 4 products:

• GitLab !44327 (merged)
• Omnibus omnibus-gitlab!4822 (merged)
• Runner gitlab-runner!2610 (merged)
• Charts gitlab-org/charts/gitlab!1699 (merged)