Use new method/field to get StagedApexInfo[]

This reduces the calls to the heavy operation
(IApexService.getStagedApexInfos) a lot.

Bug: 370712193
Test: Presubmit
Change-Id: Ie67b468b1b7474ae88da144b7c4ba1072810e8f5
diff --git a/android/virtmgr/src/payload.rs b/android/virtmgr/src/payload.rs
index 81e02b7..5811314 100644
--- a/android/virtmgr/src/payload.rs
+++ b/android/virtmgr/src/payload.rs
@@ -178,14 +178,9 @@
             let pm =
                 wait_for_interface::<dyn IPackageManagerNative>(PACKAGE_MANAGER_NATIVE_SERVICE)
                     .context("Failed to get service when prefer_staged is set.")?;
-            let staged =
-                pm.getStagedApexModuleNames().context("getStagedApexModuleNames failed")?;
-            for name in staged {
-                if let Some(staged_apex_info) =
-                    pm.getStagedApexInfo(&name).context("getStagedApexInfo failed")?
-                {
-                    list.override_staged_apex(&staged_apex_info)?;
-                }
+            let staged = pm.getStagedApexInfos().context("getStagedApexInfos failed")?;
+            for apex in staged {
+                list.override_staged_apex(&apex)?;
             }
         }
         Ok(list)