Problem was that a failing rename just left the partitions at the state
it was at the failure.

Solution was to try to revert the started rename if a failure occured.

mysql-test/r/partition_not_embedded.result:
  Bug#30102: Rename table does corrupt tables with partition files on failure
  
  New result file
mysql-test/t/partition_not_embedded.test:
  Bug#30102: Rename table does corrupt tables with partition files on failure
  
  New test file
  (list_files does not report the files in embedded)
sql/ha_partition.cc:
  Bug#30102: Rename table does corrupt tables with partition files on failure
  
  Better error handling for rename partitions (reverting the started rename
  operation)
  
  Different order of files for delete.
sql/handler.cc:
  Bug#30102: Rename table does corrupt tables with partition files on failure
  
  Tries to remove as many table files as possible
  if the first delete succeeds.