Move the rewrite query logic into drop_table() and rename_table()
respectively. Move away from use my_strmov_quoted_identifer() in favor
of always just using "`", that's what the old implementation actually
did.

Remove now unused args "new_dbname" and "new_tabname" from
log_schema_op* functions.

Change-Id: I2c019fb047b57e6282f1c80984b7673dd574fb17