Replace remaining shell references with service manager

services/tracing/manifest.json

 {
   "manifest_version":  1,
   "name": "service:tracing",
   "display_name": "Tracing Collector",
   "capabilities": {
     "provided": {
       "app": [
         "tracing::mojom::Factory",
         "tracing::mojom::Collector",
         "tracing::mojom::StartupPerformanceDataCollector"
       ]
     },
     "required": {
-      "service:shell": [ "shell:all_users" ]
+      "service:service_manager": [ "service_manager:all_users" ]
     }
   }
 }