Add LD SDK key to configmanager service

Summary:
When specified, the configmanager service reaches out to LaunchDarkly to fetch feature flag values.
This diff updates the YAML so that the configmanager reads the SDK key if present in a configmap.

Test Plan: testing cluster

Reviewers: nserrino, vihang

Reviewed By: vihang
Signed-off-by: Michelle Nguyen <michellenguyen@pixielabs.ai>

Differential Revision: https://phab.corp.pixielabs.ai/D11663

GitOrigin-RevId: 0ee39fd82f236abb8becf3c2db7467fe1fbade52

k8s/cloud/base/config_manager_deployment.yaml

@@ -61,6 +61,12 @@ spec:
             configMapKeyRef:
               name: pl-sentry-dsn-config
               key: PL_DEV_SENTRY
+        - name: PL_LD_SDK_KEY
+          valueFrom:
+            configMapKeyRef:
+              name: pl-ld-config
+              key: PL_LD_SDK_KEY
+              optional: true
         volumeMounts:
         - name: certs
           mountPath: /certs

k8s/cloud_deps/public/configs.yaml

@@ -16,6 +16,7 @@ metadata:
 data:
   # Set this key to enable launchdarkly to gate development features.
   PL_LD_CLIENT_ID: ""
+  PL_LD_SDK_KEY: ""
 ---
 apiVersion: v1
 kind: ConfigMap