github-actions: Add KernelCI support to CBR

Allow callers to skip the kselftests stage entirely. Useful for CBR
where kselftest coverage is minimal due to the old kernel.

- Add skip_kselftests boolean input (default: false)
- Gate test-kselftest and compare-results jobs on !skip_kselftests
- Allow create-pr when kselftest result is 'skipped'
- Skip kselftest log downloads and stats when kselftests are skipped

Signed-off-by: Shreeya Patel <spatel@ciq.com>

Author: shreeya-patel98

.container_build_image

@@ -0,0 +1,2 @@
+cbr-7.9-kernel-builder
+

.github/workflows/kernel-build-and-test-multiarch.yml

@@ -0,0 +1,14 @@
+name: Automated kernel build and test x86_64 & aarch64
+
+on:
+  push:
+    branches:
+      - '*_ciqcbr7_9'
+
+jobs:
+  kernelCI:
+    uses: ctrliq/kernel-src-tree/.github/workflows/kernel-build-and-test-multiarch.yml@main
+    with:
+      architectures: 'x86_64'
+      skip_kselftests: true
+    secrets: inherit