scripts: skip checksum for custom-provided workloads

Skip sha1sum verification for firmware files that were
provided via CH_CUSTOM_FIRMWARE or CH_CUSTOM_OVMF environment
variables.  Custom files will not match the expected checksums,
so we filter them out of the sha1sums list before running
sha1sum --check.

Updated scripts:
- run_integration_tests_x86_64.sh
- run_integration_tests_aarch64.sh

Assisted-by: GitHub Copilot:Claude-Opus-4.6

Signed-off-by: Muminul Islam <muislam@microsoft.com>

scripts/run_integration_tests_aarch64.sh

@@ -141,9 +141,17 @@ update_workloads() {
 
     pushd "$WORKLOADS_DIR" || exit
 
-    if ! sha1sum sha1sums-aarch64-common --check; then
-        echo "sha1sum validation of images failed, remove invalid images to fix the issue."
-        exit 1
+    # Skip checksum verification for custom-provided workloads
+    if [ -n "$CH_CUSTOM_OVMF" ]; then
+        if ! grep -v "CLOUDHV_EFI.fd" sha1sums-aarch64-common | sha1sum --check; then
+            echo "sha1sum validation of images failed, remove invalid images to fix the issue."
+            exit 1
+        fi
+    else
+        if ! sha1sum sha1sums-aarch64-common --check; then
+            echo "sha1sum validation of images failed, remove invalid images to fix the issue."
+            exit 1
+        fi
     fi
     popd || exit