test: update test manifests to use Fedora 34

Move from using 'zram' to 'zram-generator-defaults' in the ostree bootiso
testing manifest. More information is available in Fedora 33 Change
document [1].

Add org.osbuild.kernel-cmdline stage to fedora-boot.json manifest
because of change in how grub handles the kernel command line arguments
[2].

GRUB2 Stage 2 checksums in assemblers test are updated. The change have
been verified by building the fedora-boot.json manifest with each checked
filesystem and booting the image in QEMU with legacy mode.

[1] https://fedoraproject.org/wiki/Changes/SwapOnZRAM
[2] https://github.com/osbuild/osbuild-composer/pull/982#issuecomment-697356929

Signed-off-by: Tomas Hozza <thozza@redhat.com>

test/data/manifests/filesystem.mpp.json

@@ -2,9 +2,9 @@
   "pipeline": {
     "build": {
       "mpp-import-pipeline": {
-        "path": "f32-build.json"
+        "path": "f34-build.json"
       },
-      "runner": "org.osbuild.fedora32"
+      "runner": "org.osbuild.fedora34"
     },
     "stages": [
       {
@@ -15,12 +15,12 @@
           ],
           "mpp-depsolve": {
             "architecture": "x86_64",
-            "module-platform-id": "f32",
-            "baseurl": "https://rpmrepo.osbuild.org/v1/anon/f32/f32-x86_64-fedora-20201010/",
+            "module-platform-id": "f34",
+            "baseurl": "https://rpmrepo.osbuild.org/v2/mirror/public/f34/f34-x86_64-fedora-20210512/",
             "repos": [
               {
                 "id": "default",
-                "baseurl": "https://rpmrepo.osbuild.org/v1/anon/f32/f32-x86_64-fedora-20201010/"
+                "baseurl": "https://rpmrepo.osbuild.org/v2/mirror/public/f34/f34-x86_64-fedora-20210512/"
               }
             ],
             "packages": [