Modify branch-push Github Action to fully prevent runs on forks

Currently the "branch push" Github Action workflow (`branch_push_workflow.yml`) will still attempt to set-up a virtual machine and run a job when triggered on a fork, even though the job is a no-op. This can be prevented by moving the line:

`if: github.repository == 'ESCOMP/CAM'`

from the multiple locations it is currently to right below the job name instead, i.e.:

```
issue_closer:
if: github.repository == 'ESCOMP/CAM'
```

This will ensure that this particular job is skipped entirely when a user pushes to a fork of the ESCOMP/CAM repo, and instead should only trigger via a push (e.g. from a merged PR) to ESCOMP/CAM itself.