Remove specific PF testing step in CI (#2569)

Right now, our PF tests run twice in CI: once in the `make test` step
and once in the `make -C pkg/pf test` step. This adds a needless 2
minutes to our CI time.

The test duplication was caused when we moved `pf` into `pkg`.

.github/workflows/build-and-test.yml

@@ -47,8 +47,6 @@ jobs:
         run: cd pkg/pf && make build
       - name: Test
         run: make test
-      - name: Test PF
-        run: cd pkg/pf && make test
       - name: Test Dynamic
         run: cd dynamic && make test
       - name: Upload coverage reports to Codecov