Increase Pagelen Limit for Pull Request Branch Search

When creating a pull request and searching for branches, the current pagelen limit is set to 25. In scenarios where there are more than 25 branches matching the search criteria (e.g., branches with the "test" keyword), only the first 25 results are listed. This limitation becomes apparent when there are, for instance, 100 relevant branches. To enhance usability and accommodate larger repositories, I propose increasing the pagelen limit for pull request branch searches to 100. This adjustment will ensure a more comprehensive and efficient branch discovery process during pull request creation.

Potential workaround will be to create a pull request between available source and destination branches. Once created, you can click on "..." after the approve button, select the edit option, and you can change the destination branch.

Issue Summary

When creating a pull request and searching for branches, the current pagelen limit is set to 25. In scenarios where there are more than 25 branches matching the search criteria (e.g., branches with the "test" keyword), only the first 25 results are listed. This limitation becomes apparent when there are, for instance, 100 relevant branches. 

The issue of the 25 pagelen occurs even when selecting the destination of a pull request by clicking on the destination branch in the header of the pull request page.

It also occurs on the branches page when clicking on a branch, which takes us to branch compare. The issue is not reproducible when clicking on the three dots in the pull request page, then editing it, or when on the branches page clicking on the three dots and selecting compare view.

Steps to Reproduce

This can only be reproduced under certain specific circumstances:

1. Make sure to create/have branches (more than 30) with a common string, for example: abc-1, abc-2.
2. When creating a pull request, try selecting a branch in the source or destination field that hasn't been updated recently, for instance, the abc-25 branch which was last updated a long time ago. If we list branches with the string "abc", it should be around the 30th or 31st position in the search list.

Expected Results

In the branch dropdown list, all matched branches will be listed, including the searched branch.

Actual Results

In the branch dropdown list, only the top 25 branches with the latest updates will be listed, not beyond that.

Workaround

workaround would be to create a pull request between the available source and destination branches. Once created, you can click on "..." after the approve button, select the edit option, and then change the destination branch