[web] removed pagination logic from thread picker

Summary:
removed pagination logic as discussed in Linear. Now if there are more than 5 threads, they will all just render instead of being paginated

Next steps:

1. Implement the search logic

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Linear task: ENG-1847

Test Plan:
Please view the attached screenshots to see the before and after of the changes I made:

Before:

6 threads would cause the picker to paginate and show the first 5 threds

After:

Now all 6 threads are shown

Reviewers: atul, rohan, abosh

Reviewed By: atul, rohan

Subscribers: ashoat, tomek, atul, abosh

Differential Revision: https://phab.comm.dev/D5230