[BugFix] fix mysql external table clause (backport #50901)

[mergify]

Why I'm doing:

To avoid this mysql stament

SELECT id_tinyint, id_smallint, id_int, id_bigint, id_float, id_double, id_decimal, id_date, id_datetime, id_char, id_varchar FROM mysql_external_default WHERE (id_varchar IS NOT NULL) AND (

It happens only when runtime filter is involved:

• there is runtime filter on mysal scan node
• but there is no value in runtime filter
• we don't handle that properly and add "AND(" to sql stmt

What I'm doing:

Fixes #50900

What type of PR is this:

• BugFix
• Feature
• Enhancement
• Refactor
• UT
• Doc
• Tool

Does this PR entail a change in behavior?

• Yes, this PR will result in a change in behavior.
• No, this PR will not result in a change in behavior.

If yes, please specify the type of change:

• Interface/UI changes: syntax, type conversion, expression evaluation, display information
• Parameter changes: default values, similar parameters but with different default values
• Policy changes: use new policy to replace old one, functionality automatically enabled
• Feature removed
• Miscellaneous: upgrade & downgrade compatibility, etc.

Checklist:

• I have added test cases for my bug fix or my new feature
• This pr needs user documentation (for new or modified features or behaviors)
  • I have added documentation for my new feature or new function
• This is a backport pr

Bugfix cherry-pick branch check:

• I have checked the version labels which the pr will be auto-backported to the target branch
  • 3.3
  • 3.2
  • 3.1
  • 3.0
  • 2.5

---

This is an automatic backport of pull request #50901 done by [Mergify](https://mergify.com). ## Why I'm doing:

To avoid this mysql stament

SELECT id_tinyint, id_smallint, id_int, id_bigint, id_float, id_double, id_decimal, id_date, id_datetime, id_char, id_varchar FROM mysql_external_default WHERE (id_varchar IS NOT NULL) AND (

It happens only when runtime filter is involved:

• there is runtime filter on mysal scan node
• but there is no value in runtime filter
• we don't handle that properly and add "AND(" to sql stmt

What I'm doing:

Fixes #50900

What type of PR is this:

• BugFix
• Feature
• Enhancement
• Refactor
• UT
• Doc
• Tool

Does this PR entail a change in behavior?

• Yes, this PR will result in a change in behavior.
• No, this PR will not result in a change in behavior.

If yes, please specify the type of change:

• Interface/UI changes: syntax, type conversion, expression evaluation, display information
• Parameter changes: default values, similar parameters but with different default values
• Policy changes: use new policy to replace old one, functionality automatically enabled
• Feature removed
• Miscellaneous: upgrade & downgrade compatibility, etc.

Checklist:

• I have added test cases for my bug fix or my new feature
• This pr needs user documentation (for new or modified features or behaviors)
  • I have added documentation for my new feature or new function
• This is a backport pr