Fix AIAP manifest branch checkout behavior

Even when specifying a manifest branch in the AIAP overrides, the
entrypoint script overrides/disables the checkout behavior of the
airshipctl document pull script if AIRSHIP_CONFIG_PHASE_REPO_REF is not
set. This change updates the entrypoint script to check if
AIRSHIP_CONFIG_PHASE_REPO_BRANCH is specified before overriding the
checkout behavior.

Signed-off-by: Drew Walters <drewwalters@microsoft.com>
Change-Id: Ibb2798201f8e02333289f193355f3aa2a6c627ad

tools/airship-in-a-pod/runner/assets/entrypoint.sh

@@ -68,7 +68,7 @@ set -x
 
 export AIRSHIP_CONFIG_MANIFEST_DIRECTORY="/opt/manifests"
 ./tools/deployment/22_test_configs.sh
-if [[ -n "$AIRSHIP_CONFIG_PHASE_REPO_REF" ]]; then
+if [[ -n "$AIRSHIP_CONFIG_PHASE_REPO_REF" || -n "$AIRSHIP_CONFIG_PHASE_REPO_BRANCH" ]]; then
   export NO_CHECKOUT="false"
 else
   export NO_CHECKOUT="true"