Sending a request with a permissions filter on Bitbucket with many users takes a lot of time.

Issue Summary

Sending a request with a permissions filter on Bitbucket with many users takes a lot of time.

When using the `users` API accordingly with the documentation

When the request includes a permissions filter, it takes ≈10 sec for 27k users.
1 /rest/api/latest/users?permission.1=REPO_READ&permission.1.repositoryId=5736&start=0&limit=20&avatarSize=32
When the request is sent without a permissions filter, it takes ≈100 ms for the same 27k users.
1 /rest/api/latest/users?start=0&limit=20&avatarSize=32

Steps to Reproduce

When the request includes a permissions filter, it takes ≈10 sec for 27k users.
1 /rest/api/latest/users?permission.1=REPO_READ&permission.1.repositoryId=5736&start=0&limit=20&avatarSize=32
When the request is sent without a permissions filter, it takes ≈100 ms for the same 27k users.
1 /rest/api/latest/users?start=0&limit=20&avatarSize=32
 

Expected Results

Sending a request with a permissions filter on Bitbucket with many users will be faster than 1 sec.

Actual Results

Sending a request with a permissions filter on Bitbucket with many users takes a lot of time.

Workaround

Using repository scoped permissions endpoint that accepts a user filter, it doesn't take nearly as long.

However, there's no filtering by permission for that currently since that only returns the highest permission for users to a repo.