Run CI all on the Fedora images

... to simplify, and to allow using recent packages.

We were using Debian because previously we were using Ubuntu,
and that was because Ubuntu was the native distribution of
Travis even before we were running CI in any kind of container;
so there seems to have been no specific intent to use a non-Fedora OS,
at least originally.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

.cirrus.yml

@@ -32,7 +32,6 @@ env:
     # Google-cloud VM Images
     IMAGE_SUFFIX: "c20250422t130822z-f42f41d13"
     FEDORA_CACHE_IMAGE_NAME: "fedora-${IMAGE_SUFFIX}"
-    DEBIAN_CACHE_IMAGE_NAME: "debian-${IMAGE_SUFFIX}"
 
     # Container FQIN's (include bleeding-edge development-level container deps.)
     FEDORA_CONTAINER_FQIN: "quay.io/libpod/fedora_podman:${IMAGE_SUFFIX}"
@@ -48,7 +47,7 @@ validate_task:
     # under Cirrus-CI, due to challenges obtaining the starting commit ID.
     # Only do validation for PRs.
     only_if: $CIRRUS_PR != ''
-    gce_instance: &debian_vm
+    gce_instance: &fedora_vm
         image_project: libpod-218412
         zone: "us-central1-f"
         cpu: 2
@@ -56,7 +55,7 @@ validate_task:
         # Required to be 200gig, do not modify - has i/o performance impact
         # according to gcloud CLI tool warning messages.
         disk: 200
-        image_name: ${DEBIAN_CACHE_IMAGE_NAME}
+        image_name: ${FEDORA_CACHE_IMAGE_NAME}
     env:
         HOME: "/root"  # default unset, needed by golangci-lint.
     script: |
@@ -68,7 +67,7 @@ validate_task:
 
 cross_task:
     only_if: &not_docs $CIRRUS_CHANGE_TITLE !=~ '.*CI:DOCS.*'
-    gce_instance: *debian_vm
+    gce_instance: *fedora_vm
     script: make cross
 
 
@@ -77,7 +76,7 @@ test_task:
     depends_on:
         - validate
     only_if: *not_docs
-    gce_instance: *debian_vm
+    gce_instance: *fedora_vm
     matrix:
         - name: "Test"
           env:
@@ -98,15 +97,7 @@ test_skopeo_task:
     only_if: *not_docs
     depends_on:
         - validate
-    gce_instance:
-        image_project: libpod-218412
-        zone: "us-central1-f"
-        cpu: 2
-        memory: "4Gb"
-        # Required to be 200gig, do not modify - has i/o performance impact
-        # according to gcloud CLI tool warning messages.
-        disk: 200
-        image_name: ${FEDORA_CACHE_IMAGE_NAME}
+    gce_instance: *fedora_vm
     matrix:
         - name: "Skopeo Test"
           env:
@@ -142,7 +133,6 @@ meta_task:
         # Space-separated list of images used by this repository state
         IMGNAMES: |
             ${FEDORA_CACHE_IMAGE_NAME}
-            ${DEBIAN_CACHE_IMAGE_NAME}
         BUILDID: "${CIRRUS_BUILD_ID}"
         REPOREF: "${CIRRUS_REPO_NAME}"
         GCPJSON: ENCRYPTED[04306103eee1933f87deb8a5af6514a7e3164aa589d6079abc0451eb2360879430ed020d6e025ca64ef667138ce9d786]