Integration test for RPM-installed Zui

[philrz]

In https://github.com/brimdata/brim/pull/1985#discussion_r766055049 it was acknowledged that we dropped the test automation that installed via the RPM package and ran the integration tests on CentOS. Since we continue to create an RPM installer for each release, it would indeed be good for us to have thorough test coverage for it to catch regressions.

Since the time of that comment, CentOS 8 has been deprecated and Rocky Linux has now taken up the former CentOS mission of RHEL compatibility, so it's the likely candidate to be used as the basis for such a test.