[Image Builder] Cannot specify the desired kernel version

Issue

• While composing a standard RHEL image, the latest kernel is always installed, even when the previous version was explicitly mentioned in the blueprint. This is not the expected behavior.

• While composing an edge-commit, both kernels are installed (whereas the depsolve looks good), and rpm-ostree fails due to this:

  Stage: org.osbuild.ostree.preptree
  Output:
  :
  Preparing kernel
  error: Finalizing rootfs: During kernel processing: Multiple vmlinuz- in usr/lib/ostree-boot, occurrences 'usr/lib/ostree-boot/vmlinuz-5.14.0-427.33.1.el9_4.x86_64' and 'usr/lib/ostree-boot/vmlinuz-5.14.0-427.35.1.el9_4.x86_64'
  Traceback (most recent call last):
   File "/run/osbuild/bin/org.osbuild.ostree.preptree", line 176, in <module>
     r = main(args["tree"], args["options"])
   File "/run/osbuild/bin/org.osbuild.ostree.preptree", line 169, in main
     subprocess.run(["rpm-ostree", "compose", "postprocess",
   File "/usr/lib64/python3.9/subprocess.py", line 528, in run
     raise CalledProcessError(retcode, process.args,
  subprocess.CalledProcessError: Command '['rpm-ostree', 'compose', 'postprocess', '/run/osbuild/tree', '/tmp/tmpjh2zneuq.json']' returned non-zero exit status 1.