extraneous file

Online/fast ALTER TABLE of a partitioned table may leave
temporary file in database directory.

Fixed by removing unnecessary call to
handler::ha_create_handler_files(), which was creating
partitioning definition file.

mysql-test/r/partition_innodb.result:
  A test case for BUG#46483.
mysql-test/t/partition_innodb.test:
  A test case for BUG#46483.
sql/unireg.cc:
  Do not call ha_create_handler_files() when we were requested
  to create only dot-frm file.