Non-functional changes that clean up test cases.

1. Change the text of 2 error messages in sql/share/errmsg-utf8.txt
   so that they can also be used for general tablespaces.
2. Clean up and refactor the code that validates CREATE TABLE
   statements in ha_innodb.cc.
3. Change the text of a few error messages in ha_innodb.cc so that
   they can also be used for general tablespaces.
4. Clean up all affected test cases, especially, getting the
   add_suppression messages out of the result files.

Approved by Vasil in rb#6807