Remove the len(all_code) > 10 fallback in the _validate method that
was overriding the LLM validation response. Previously, any code longer
than 10 characters would cause validation to automatically pass regardless
of the LLM's assessment, making the validation check ineffective.
The fix ensures validation status is determined solely by whether the LLM
response contains 'PASS', making the validation meaningful.
A regression test was added to verify that FAIL/REJECTED LLM responses
are properly handled even for long code blocks.
ISSUES CLOSED: #10746
