fmf: Drop cockpit packages from test dependencies

This causes the package to be (formally) upgraded in RHEL/CentOS 8:
there cockpit is already at version 264.1 (from the rhel-9.0 stable
branch), but our version on main is 264. Due to this it "upgrades" to an
actually older version, and does not test current changes.

test/verify.fmf

@@ -1,12 +1,5 @@
 summary: Run browser integration tests on the host
 require:
-  - cockpit
-  - cockpit-kdump
-  - cockpit-networkmanager
-  - cockpit-packagekit
-  - cockpit-sosreport
-  - cockpit-storaged
-  - cockpit-tests
   # build/test infra dependencies
   - git
   - make