feat: [CI-8680]: replace config for gitness jwt

Author: devkimittal

332-ci-manager/config/ci-manager-config.yml

@@ -392,7 +392,7 @@ ciExecutionServiceConfig:
       dockerBuildxAcrConfig:
         name: github.com/drone-plugins/drone-buildx-acr@refs/tags/v1.0.0
   gitnessConfig:
-    jwtSecret: IC04LYMBf1lDP5oeY4hupxd4HJhLmN6azUku3xEbeE3SUx5G3ZYzhbiwVtK4i7AmqyU9OZkwB4v8E9qM
+    jwtSecret: ${GITNESS_JWT_SECRET:-"IC04LYMBf1lDP5oeY4hupxd4HJhLmN6azUku3xEbeE3SUx5G3ZYzhbiwVtK4i7AmqyU9OZkwB4v8E9qM"}
 
 
 pmsSdkExecutionPoolConfig: