gitlab: separate pipeline generators per architecture

While the first child pipeline generator can generate configs for all
architectures, split it just like we do with the ostree pipeline
generator to share the work and speed up the manifest generation a bit.

.gitlab-ci.yml

@@ -41,7 +41,7 @@ init:
   script:
     - schutzbot/update_github_status.sh start
 
-generate-build-config:
+generate-build-config-x86_64:
   stage: gen
   extends: .terraform
   variables:
@@ -56,12 +56,35 @@ generate-build-config:
     paths:
       - build-config.yml
 
-image-build-trigger:
+generate-build-config-aarch64:
+  stage: gen
+  extends: .terraform
+  variables:
+    RUNNER: aws/fedora-38-aarch64
+    INTERNAL_NETWORK: "true"
+    PYTHONUNBUFFERED: 1
+  script:
+    - sudo dnf -y install go python3 gpgme-devel s3cmd
+      osbuild osbuild-luks2 osbuild-lvm2 osbuild-ostree osbuild-selinux
+    - ./test/generate-build-config build-config.yml
+  artifacts:
+    paths:
+      - build-config.yml
+
+image-build-trigger-x86_64:
+  stage: test
+  trigger:
+    include:
+      - artifact: build-config.yml
+        job: generate-build-config-x86_64
+    strategy: depend
+
+image-build-trigger-aarch64:
   stage: test
   trigger:
     include:
       - artifact: build-config.yml
-        job: generate-build-config
+        job: generate-build-config-aarch64
     strategy: depend
 
 generate-ostree-build-config-x86_64:

test/generate-build-config

@@ -8,9 +8,6 @@ from tempfile import TemporaryDirectory
 
 import imgtestlib as testlib
 
-# TEST SELECTION
-ARCHITECTURES = ["x86_64", "aarch64"]
-
 PUSH_CONTAINER = "./tools/ci/push-container.sh"
 
 
@@ -35,7 +32,7 @@ def generate_manifests(outputdir):
     Generate all manifest using the default config map and return a dictionary mapping each manifest file to the
     manifest data and its ID.
     """
-    arches_arg = ",".join(ARCHITECTURES)
+    arches_arg = os.uname().machine
     cmd = ["go", "run", "./cmd/gen-manifests",
            "-cache", os.path.join(testlib.TEST_CACHE_ROOT, "rpmmd"),
            "-output", outputdir,