MDEV-24586: remove mysql_to_mariadb.sql

This script is unused and unmaintained.

The logic is implemented in scripts/mysql_system_tables_fix.sql that forms part of mysql_upgrade

Its components:

  alter table mysql.user drop column `password_last_changed`, drop column `password_lifetime`, drop column `account_locked`;

has a friendlier migration path coming MDEV-24122

  alter table mysql.user change column `authentication_string` `auth_string` text COLLATE utf8_bin NOT NULL;

Already part of scripts/mysql_system_tables_fix.sql

  alter table mysql.user add column  `Password` char(41) CHARACTER SET latin1 COLLATE latin1_bin NOT NULL DEFAULT '' after `user`, add column  `is_role` enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N' after `auth_string`;

  alter table mysql.user add column `default_role` char(80) COLLATE utf8_bin NOT NULL DEFAULT '', add column `max_statement_time` decimal(12,6) NOT NULL DEFAULT '0.000000';

corrected in MDEV-23201 to be in the right order.

  update mysql.user set `password`=`auth_string`, plugin='' where plugin="mysql_native_password";

Is handled in server in the function acl_load.

scripts/CMakeLists.txt

@@ -99,7 +99,6 @@ INSTALL(FILES
   ${CMAKE_CURRENT_SOURCE_DIR}/mysql_test_db.sql
   ${CMAKE_CURRENT_SOURCE_DIR}/fill_help_tables.sql
   ${CMAKE_CURRENT_SOURCE_DIR}/mysql_test_data_timezone.sql
-  ${CMAKE_CURRENT_SOURCE_DIR}/mysql_to_mariadb.sql
   ${CMAKE_CURRENT_BINARY_DIR}/maria_add_gis_sp.sql
   ${CMAKE_CURRENT_BINARY_DIR}/maria_add_gis_sp_bootstrap.sql
   ${FIX_PRIVILEGES_SQL}