Merge pull request #42450 from Q-Lee/fix-unbound

Automatic merge from submit-queue

Fixing unbound bash variable.

**What this PR does / why we need it**: this fixes a bug introduced in 1.6 for ABAC.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #

**Special notes for your reviewer**: without this, we hit an unbound variable and fail to bring up the kube-apiserver with ABAC enabled.

**Release note**:

```release-note
```

cluster/gce/gci/configure-helper.sh

@@ -1081,6 +1081,7 @@ function start-kube-apiserver {
 
 
   local authorization_mode="RBAC"
+  local -r src_dir="${KUBE_HOME}/kube-manifests/kubernetes/gci-trusty"
 
   # Create the ABAC file only if it's explicitly requested.
   if [[ -n "${ENABLE_LEGACY_ABAC_16_ONLY:-}" ]]; then
@@ -1111,7 +1112,6 @@ function start-kube-apiserver {
     webhook_config_mount="{\"name\": \"webhookconfigmount\",\"mountPath\": \"/etc/gcp_authz.config\", \"readOnly\": false},"
     webhook_config_volume="{\"name\": \"webhookconfigmount\",\"hostPath\": {\"path\": \"/etc/gcp_authz.config\"}},"
   fi
-  local -r src_dir="${KUBE_HOME}/kube-manifests/kubernetes/gci-trusty"
   params+=" --authorization-mode=${authorization_mode}"
 
   local container_env=""