executor: bootstrap SQLs are not treated as internal queries in statement summary (#17024)

[sre-bot]

cherry-pick #17024 to release-4.0

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What problem does this PR solve?

Problem Summary:
Some SQLs executed in bootstrap phase are not marked as internal queries. By default, internal queries are ignored in statement summary. But these SQLs still appear in statement summary.
For example, these SQLs are executed in bootstrap:

select variable_value from mysql.tidb where variable_name = 'system_tz'
select variable_value from mysql.tidb where variable_name = 'new_collation_enabled'

After This PR (after bootstrap):

mysql> select sample_user, exec_count, digest_text from information_schema.statements_summary\G
*************************** 1. row ***************************
sample_user: root
 exec_count: 1
digest_text: show tables
*************************** 2. row ***************************
sample_user: root
 exec_count: 1
digest_text: show databases
*************************** 3. row ***************************
sample_user: root
 exec_count: 1
digest_text: use test
*************************** 4. row ***************************
sample_user: NULL
 exec_count: 2
digest_text: select variable_value from mysql . tidb where variable_name = ?
4 rows in set (0.04 sec)

What is changed and how it works?

What's Changed:
Treat the SQLs whose users are empty as internal queries.

Related changes

• Need to cherry-pick to the release branch

Check List

Tests

• Manual test (add detailed scripts or steps below)
  After(after bootstrap):

mysql> select sample_user, digest_text from information_schema.statements_summary\G
*************************** 1. row ***************************
sample_user: root
digest_text: show tables
*************************** 2. row ***************************
sample_user: root
digest_text: show databases
*************************** 3. row ***************************
sample_user: root
digest_text: use test
3 rows in set (0.01 sec)

Side effects

N/A

Release note

• Mark bootstrap statements as internal queries in statement summary.

[sre-bot]

/run-all-tests

[AilinKid]

LGTM

[Deardrops]

LGTM