IOC test framework: Use PVA as well as CA

As of #8298 we should have a pv access server running on nearly every IOC now. I would like to test these using the ioc test framework using a python-pva client as we do with channel access.

## Notes
Whoever picks this up may wish to talk to @LowriJenkins, who has previously completed the precursor work.

## acceptance criteria
- [x] IOC test framework/cachannel is modified to allow PVA connections
- [ ] Jenkins job created for running all tests under PVA
- [ ] Appropriate flags set in IOCs to not test them with PVA where appropriate
- [ ] Any failures have tickets created to fix OR a skip_if condition applied.

## Planning
08/05/2025 - 0:22:30