executor: cleanup entries from mysql.db on revoke (#38370)

[ti-chi-bot]

This is an automated cherry-pick of #38370

What problem does this PR solve?

Issue Number: close #38363

Problem Summary:

Cleanup records in mysql.db where all fields are set to N.

sql> select * from mysql.db where user='u1' and host='%'\G
*************************** 1. row ***************************
                 Host: %
                   DB: te%
                 User: u1
          Select_priv: Y
          Insert_priv: Y
          Update_priv: N
          Delete_priv: N
          Create_priv: N
            Drop_priv: N
           Grant_priv: N
      References_priv: N
           Index_priv: N
           Alter_priv: N
Create_tmp_table_priv: N
     Lock_tables_priv: N
     Create_view_priv: N
       Show_view_priv: N
  Create_routine_priv: N
   Alter_routine_priv: N
         Execute_priv: N
           Event_priv: N
         Trigger_priv: N
1 row in set (0.0042 sec)

sql> REVOKE SELECT ON `te%`.* FROM 'u1'@'%';
Query OK, 0 rows affected (0.0133 sec)

sql> select * from mysql.db where user='u1' and host='%'\G
*************************** 1. row ***************************
                 Host: %
                   DB: te%
                 User: u1
          Select_priv: N
          Insert_priv: Y
          Update_priv: N
          Delete_priv: N
          Create_priv: N
            Drop_priv: N
           Grant_priv: N
      References_priv: N
           Index_priv: N
           Alter_priv: N
Create_tmp_table_priv: N
     Lock_tables_priv: N
     Create_view_priv: N
       Show_view_priv: N
  Create_routine_priv: N
   Alter_routine_priv: N
         Execute_priv: N
           Event_priv: N
         Trigger_priv: N
1 row in set (0.0043 sec)

sql> REVOKE INSERT ON `te%`.* FROM 'u1'@'%';
Query OK, 0 rows affected (0.0216 sec)

sql> select * from mysql.db where user='u1' and host='%'\G
Empty set (0.0034 sec)

What is changed and how it works?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Database level privileges are cleaned up correctly 

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• bb7133
• xhebox

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[xhebox]

/cc @dveeden

[bb7133]

LGTM

[xhebox]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 8ddd391

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