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/sql_class.h

@@ -4177,6 +4177,13 @@ public:
     locked_tables_mode= mode_arg;
   }
   void leave_locked_tables_mode();
+  /* Relesae transactional locks if there are no active transactions */
+  void release_transactional_locks()
+  {
+    if (!(server_status &
+          (SERVER_STATUS_IN_TRANS | SERVER_STATUS_IN_TRANS_READONLY)))
+      mdl_context.release_transactional_locks();
+  }
   int decide_logging_format(TABLE_LIST *tables);
   /*
    In Some cases when decide_logging_format is called it does not have all