Because Forgejo run mysqld with `--innodb-flush-method=nosync` to speed
up the test suite, there are situations where a larger, database-wide
operation does not always fully manifest until later, not even when it
is wrapped in a transaction, nor when we use `FLUSH TABLES` and similar
methods.
In the case of the MySQL collation test, this *sometimes* results in the
database still responding with the old collation to a reader, even after
an `ALTER DATABASE ... COLLATE ...`.
In order to be able to still use the aforementioned flag and enjoy its
benefits, add a five second sleep between `db.ConvertDatabaseTable()`
and `db.CheckCollations()` in the `TestDatabaseCollation()` set of
tests.
This is not a fix - I don't think there is one possible -, but a
workaround. If it breaks again, the correct fix will be to remove the
flag from `mysqld` (it's not a supported flag to begin with).
Signed-off-by: Gergely Nagy <forgejo@gergo.csillger.hu>