Merge ICompOsKeyService into ICompOsService

 * Remove the compos_key_main executable and key_service_vm_config.json,
   since the service is now provided by ICompOsService/compsvc.
 * Updated ComosKeyTestCase to use the same VM / service.

Bug: 161471326
Test: ComposHostTestCases

Change-Id: I8efb1158a90a06d0ba123da98c90fc69ff09d738
diff --git a/compos/src/compsvc_main.rs b/compos/src/compsvc_main.rs
index 5c5da22..48e37b6 100644
--- a/compos/src/compsvc_main.rs
+++ b/compos/src/compsvc_main.rs
@@ -49,7 +49,7 @@
     );
 
     let config = parse_args()?;
-    let mut service = compsvc::new_binder(config.rpc_binder, /* signer */ None)?.as_binder();
+    let mut service = compsvc::new_binder(config.rpc_binder)?.as_binder();
     if config.rpc_binder {
         debug!("compsvc is starting as a rpc service.");
         // SAFETY: Service ownership is transferring to the server and won't be valid afterward.