Migrate `mysys/errors.c`, `sql-common/errmsg.c` and a couple of
insignificant loose ends to use suffix-based, `-Wformat`-compatible
`my_snprintf` format extensions introduced in MDEV-21978
This commit is the final batch of MDEV-21978’s migration process.
While GCC `-Wformat` (with `ATTRIBUTE_FORMAT`) can catch obsolete or
malformed format string literals, formats originating from other sources
(such as those strings headers) (still) require manual review.
Thus, after all the automatic `-Wformat` complaints fixed in previous
commits, I’ve done a manual `grep` and caught these final matches.
Changed wording in error messages from MySQL to MariaDB. In
cases where the word server could be used instead it was done.
Tests that have these errors recorded were updated.