Also increase user name up to 128.
The work was started by Rucha Deodhar <rucha.deodhar@mariadb.com>,
contains audit plugin fixes by Alexey Botchkov <holyfoot@askmonty.org>.
* remove dead code (from .yy)
* remove redundant commands from the test
* extract common code into a reusable function
(get_auth_plugin, push_new_user)
* rename update_user_table->update_user_table_password
* simplify acl_update_user
* don't strdup a string that's already in a memroot
(in ACL_ROLE::ACL_ROLE(ACL_USER*))
* create parent_grantee and role_grants dynamic arrays with size 0.
to avoid any memory allocations when roles aren't used.
Don't distinguish between a "password hash" and "authentication string"
anymore. Now both are stored in mysql.user.authentication_string, both
are handled identically internally. A "password hash" is just how some
particular plugins interpret authentication string.
Set mysql.user.plugin even if there is no password. The server will use
mysql_native_password plugin in these cases, let's make it expicit.
Remove LEX_USER::pwhash.
