I would like to have following fields in ansible job.
branch (default: devel)
username (default: ansible)
So in OST, we can define which branch+ from which git repo, should be fetched,
with this we can test PRs.
It's not really possible to add what you're asking with the current way OST works in CI, since the OST job isn't building ( and shouldn't ) build any project, just test it.
The way to test PRs in Jenkins is to use the manual job  and custom RPMs, usually built by the 'build on demand' feature.
The blog  described how to do it, though we'll need to check if we support 'build on demand' for GitHub projects like ovirt-ansible.
We'll need to add the 'ansible' suite the the list of suites you can test using the manual job and to verify you can build from a patch, so you'll have a custom yum repo to provide the job to test.
can you help adding the ansible suite to the list of suites available in the manual OST Job?
do we support 'build on demand' for GitHub projects? if not, then i guess 'check-patch' job can be used if the RPM is built there
created and sent the patch.
I've also applied the patch manually, so the ansible suite is actually available now through the manual suite.
can you verify you can run the ansible suite using the manual job?
Solution was provided via 'build on demand' and adding ansible suite to the manual flow