plugin_validator skips placeholder validation inside --if tokens

[karrisanthoshigayatri]

#1801

Description

Related Issues

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

How Has This Been Tested?

Checklist

• My code follows the code style of this project.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.

[utksh1]

Thanks for tightening placeholder validation inside --if tokens. Please add regression tests for the new parsing path before merge: cover a valid placeholder in a then/else segment, an unknown placeholder in a then/else segment, and a token with multiple colon-separated pieces so we know the parser does not miss or misread placeholders. The current PR changes validator behavior but has no test coverage for it.