Revert "Microdroid: Skip instance.img checks"

Revert submission 2982081

Reason for revert: There are tests failing which needs modification. Revert for immediate mitigation.
Reverted changes: /q/submissionid:2982081

Change-Id: I20a97efe5fc78b709626c842c4f523f8003e9476
diff --git a/microdroid_manager/src/vm_secret.rs b/microdroid_manager/src/vm_secret.rs
index 7b65491..5ceedea 100644
--- a/microdroid_manager/src/vm_secret.rs
+++ b/microdroid_manager/src/vm_secret.rs
@@ -279,9 +279,9 @@
     anyhow!("{:?}", err)
 }
 
-/// Get the secretkeeper connection if supported. Host can be consulted whether the device supports
-/// secretkeeper but that should be used with caution for protected VM.
-pub fn is_sk_supported(
+// Get the secretkeeper connection if supported. Host can be consulted whether the device supports
+// secretkeeper but that should be used with caution for protected VM.
+fn is_sk_supported(
     host: &Strong<dyn IVirtualMachineService>,
 ) -> Result<Option<Strong<dyn ISecretkeeper>>> {
     let sk = if cfg!(llpvm_changes) {