Fix #9476 - Mass assign security groups only assigns selected on current page

[JackBuchanan]

Change how UID array is built in assignGroups

Description

Use MassUpdate.uid to build ID array then set MassAssign to be equal to MassUpdate array

Motivation and Context

Fix #9476 where mass assign security groups only assigns selected on current page

How To Test This

1. Select 10 records on page 1, go to next page of records and select 10 more records, now 20 in total.
2. Mass assign a security group
3. Check securitygroups_record table to ensure all records were assigned a group

Types of changes

• [x] 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 change)

Final checklist

• [x] My code follows the code style of this project found here.
• [ ] My change requires a change to the documentation.
• [x] I have read the How to Contribute guidelines.