Packit: replace files_to_sync with prepare-files

With TMT being able to fetch and run tests using git url
and ref, there's no need to sync files on every propose_downstream
Packit action.

Removing files_to_sync should be safe as we only need to sync
`.packit.yaml` which is part of Packit's default behavior already.

Other files like gating.yaml only need to exist downstream and
shouldn't need any frequent manual changes, so
we can remove those from upstream and packit file-sync too.

New setup: We use a `prepare-files` action that will operate only on
`plans/main.fmf` in downstream dist-git and update the ref with the
tag from the latest release.

Signed-off-by: Lokesh Mandvekar <lsm5@redhat.com>

.packit.yaml

@@ -9,27 +9,6 @@
 downstream_package_name: skopeo
 upstream_tag_template: v{version}
 
-# These files get synced from upstream to downstream (Fedora / CentOS Stream) on every
-# propose-downstream job. This is done so tests maintained upstream can be run
-# downstream in Zuul CI and Bodhi.
-# Ref: https://packit.dev/docs/configuration#files_to_sync
-files_to_sync:
-  - src: rpm/gating.yaml
-    dest: gating.yaml
-    delete: true
-  - src: plans/
-    dest: plans/
-    delete: true
-    mkpath: true
-  - src: systemtest/tmt/
-    dest: test/tmt/
-    delete: true
-    mkpath: true
-  - src: .fmf/
-    dest: .fmf/
-    delete: true
-  - .packit.yaml
-
 packages:
   skopeo-fedora:
     pkg_tool: fedpkg
@@ -40,6 +19,10 @@ packages:
   skopeo-eln:
     specfile_path: rpm/skopeo.spec
 
+actions:
+  prepare-files: >-
+    bash -c "sed -i 's/^\(\s*\)ref: .*/\1ref: \"${PACKIT_PROJECT_TAG}\"/' ${PACKIT_DOWNSTREAM_REPO}/plans/main.fmf"
+
 srpm_build_deps:
   - make
 

rpm/gating.yaml

@@ -1,16 +0,0 @@
---- !Policy
-product_versions:
-  - fedora-*
-decision_contexts:
-  - bodhi_update_push_stable
-  - bodhi_update_push_testing
-subject_type: koji_build
-rules:
-  - !PassingTestCaseRule {test_case_name: fedora-ci.koji-build.tier0.functional}
-
---- !Policy
-product_versions:
-  - rhel-*
-decision_context: osci_compose_gate
-rules:
-  - !PassingTestCaseRule {test_case_name: osci.brew-build.tier0.functional}