Vitess v18.0.6

Release of Vitess v18.0.6

The entire changelog for this release can be found here.

Known Issues

VTTablet runs an unnecessary DDL

In this release, with MySQL 8.0 whenever VTTablet's tabletserver goes through initialization, it finds
a diff in its internal schemacopy table and tries to apply a DDL to fix it. The DDL
is a no-op and this loop of applying the DDL continues to run.
If this problem is encountered, the following PR should be reverted to resolve it - #15859.

The release includes 28 merged Pull Requests.

Thanks to all our contributors: @GuptaManan100, @app/vitess-bot, @arthurschreiber, @shlomi-noach, @vitess-bot