Use READ COMMITTED for all MySQL transactions on busy sites

This seems like an argument to make on the 🐛 Use READ COMMITTED by default for MySQL transactions Fixed issue rather than a separate bug report.

I've been thinking about it. Since the development of issue 1650930 is moving towards a comprehensive solution including configuration, I thought it would be better to offer this simpler alternative approach in a separate issue.

This has been fixed in 🐛 Use READ COMMITTED by default for MySQL transactions Fixed .
This will not be backported to D10.0 or D9.5.