Followup to Bug#42546 Backup: RESTORE fails, thinking it finds an existing table

This patch updates lowercase_table2.test with the changed error message
CREATE TABLE produces if it fails because it finds an matching TABLE_SHARE 
in the TDC even if the .FRM/.MYD has been removed from disk.

With the changes introduced in Bug#42546, CREATE TABLE uses open_tables()
which will find the TDC entry and fail in open_table_from_share() with
ER_FILE_NOT_FOUND. Before, CREATE TABLE would not use open_tables() and
fail with ER_TABLE_EXISTS_ERROR upon finding the TDC entry in
mysql_create_table_no_lock().