[BugFix] Fix for npe NormalizePredicateRule

[ikishore]

Why I'm doing:

Fix for null pointer exception, when there are no nested children

What I'm doing:

Added null check, No side effect on functionality

Fixes #issue #52167

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

[kangkaisen]

please add the UT, thanks.

[sonarcloud]

Quality Gate passed

Issues
3 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[github-actions]

[Java-Extensions Incremental Coverage Report]

✅ pass : 0 / 0 (0%)

[github-actions]

[FE Incremental Coverage Report]

✅ pass : 2 / 2 (100.00%)

file detail

	path	covered_line	new_line	coverage	not_covered_line_detail
🔵	com/starrocks/sql/optimizer/rewrite/scalar/NormalizePredicateRule.java	2	2	100.00%	[]

[github-actions]

[BE Incremental Coverage Report]

✅ pass : 0 / 0 (0%)

[ikishore]

please add the UT, thanks.

@kangkaisen Please review. UT case added

[github-actions]

@Mergifyio backport branch-3.3

[github-actions]

@Mergifyio backport branch-3.2

[mergify]

backport branch-3.3

✅ Backports have been created

• #53087 [BugFix] Fix for npe NormalizePredicateRule (backport #52326) has been created for branch branch-3.3

[mergify]

backport branch-3.2

✅ Backports have been created

• #53088 [BugFix] Fix for npe NormalizePredicateRule (backport #52326) has been created for branch branch-3.2