[rpc_binder][test] Merge unixBootstrapFd and socketFd in binderRpcTest

This is a follow-up of the cl aosp/2267564.

Test: atest binderRpcTest
Change-Id: I5bf68197aa5f34cc3f700dcc70419fcc0acfb1ef
diff --git a/libs/binder/tests/BinderRpcTestServerConfig.aidl b/libs/binder/tests/BinderRpcTestServerConfig.aidl
index aac4b04..b2e0ef2 100644
--- a/libs/binder/tests/BinderRpcTestServerConfig.aidl
+++ b/libs/binder/tests/BinderRpcTestServerConfig.aidl
@@ -21,7 +21,6 @@
     int rpcSecurity;
     int serverVersion;
     int vsockPort;
-    int unixBootstrapFd; // Inherited from parent
-    int socketFd;
+    int socketFd; // Inherited from the parent process.
     @utf8InCpp String addr;
 }