Set verify_holes to false in RGMB FlexiblePatternGenerator mesh subgenerator calls

[shikhar413]

Bug Description

https://civet.inl.gov/job/2367026/ - reactor module test failure, likely due to the fact that verify_holes is set to true by default in the mesh subgenerator call

Steps to Reproduce

See https://civet.inl.gov/job/2367026/

Impact

Pass tests for devel branch

[Optional] Diagnostics

No response

[GiudGiud]

closing as addressed by #28317