Remove the ability to query CompOS BCC

We're no longer planning on using this soon.

Also connect to diced on demand rather than at startup, to reduce
startup latency.

Bug: 214233409
Test: atest ComposKeyTestCase
Change-Id: I91bef95beae9f8b268b2d2b12f782b72ffb006d5
diff --git a/compos/src/compsvc.rs b/compos/src/compsvc.rs
index e4cdb40..422f271 100644
--- a/compos/src/compsvc.rs
+++ b/compos/src/compsvc.rs
@@ -62,7 +62,7 @@
         if key.is_empty() {
             Err(new_binder_exception(ExceptionCode::ILLEGAL_STATE, "Key is not initialized"))
         } else {
-            Ok(self.signing_key.new_signer(key))
+            to_binder_result(self.signing_key.new_signer(key))
         }
     }
 }
@@ -118,10 +118,6 @@
             true
         })
     }
-
-    fn getBootCertificateChain(&self) -> BinderResult<Vec<u8>> {
-        to_binder_result(self.signing_key.get_boot_certificate_chain())
-    }
 }
 
 fn get_authfs_service() -> BinderResult<Strong<dyn IAuthFsService>> {