[attestation] Rename the client VM attestation API

As agreed in the doc go/pvm-remote-attestation.

Bug: 303807447
Test: m com.android.virt
Test: run ServiceVmClientApp
Change-Id: Ic954aa60d69e42773c04230af9319e660352d6a9
diff --git a/virtualizationmanager/src/aidl.rs b/virtualizationmanager/src/aidl.rs
index 5283ffe..da7dffe 100644
--- a/virtualizationmanager/src/aidl.rs
+++ b/virtualizationmanager/src/aidl.rs
@@ -1245,8 +1245,8 @@
         }
     }
 
-    fn requestCertificate(&self, csr: &[u8]) -> binder::Result<Vec<u8>> {
-        GLOBAL_SERVICE.requestCertificate(csr)
+    fn requestAttestation(&self, csr: &[u8]) -> binder::Result<Vec<u8>> {
+        GLOBAL_SERVICE.requestAttestation(csr)
     }
 }