MDEV 15532 Assertion `!log->same_pk' failed in row_log_table_apply_delete

The reason for the failure is that
thd->mdl_context.release_transactional_locks()
was called after commit & rollback even in cases where the current
transaction is still active.

For 10.2, 10.3 and 10.4 the fix is simple:
- Replace all calls to thd->mdl_context.release_transactional_locks() with
  thd->release_transactional_locks(). The thd function will only call
  the mdl_context function if there are no active transactional locks.
  In 10.6 we will better fix where we will change the return value for
  some trans_xxx() functions to indicate if transaction did close the
  transaction or not. This will avoid the need of the indirect call.

Other things:
- trans_xa_commit() and trans_xa_rollback() will automatically
  call release_transactional_locks() if the transaction is closed.
- We can't do that for the other functions as the caller of many of these
  are doing additional work (like close_thread_tables) before calling
  release_transactional_locks().
- Added missing abort_result_set() and missing DBUG_RETURN in
  select_create::send_eof()
- Fixed wrong indentation in injector::transaction::commit()

sql/wsrep_thd.cc

@@ -75,7 +75,7 @@ void wsrep_client_rollback(THD *thd)
   }
 
   /* Release transactional metadata locks. */
-  thd->mdl_context.release_transactional_locks();
+  thd->release_transactional_locks();
 
   /* release explicit MDL locks */
   thd->mdl_context.release_explicit_locks();
@@ -211,7 +211,7 @@ void wsrep_replay_sp_transaction(THD* thd)
     thd->locked_tables_list.unlock_locked_tables(thd);
     thd->variables.option_bits&= ~(OPTION_TABLE_LOCK);
   }
-  thd->mdl_context.release_transactional_locks();
+  thd->release_transactional_locks();
 
   mysql_mutex_unlock(&thd->LOCK_thd_data);
   THD *replay_thd= new THD(true);
@@ -350,7 +350,7 @@ void wsrep_replay_transaction(THD *thd)
         thd->locked_tables_list.unlock_locked_tables(thd);
         thd->variables.option_bits&= ~(OPTION_TABLE_LOCK);
       }
-      thd->mdl_context.release_transactional_locks();
+      thd->release_transactional_locks();
       /*
         Replaying will call MYSQL_START_STATEMENT when handling
         BEGIN Query_log_event so end statement must be called before