Multi_tenant is the new payload_not_root

Trying to have more fine-grained Rust configs than feature flags was
actually a terrible idea, and means extra work if I need to add
something that is multi-tenant related but not root related.

Use consistent naming throughout instead.

Bug: 302677468
Test: Builds
Change-Id: I2dfe97e8c62f24590522df89d9b373774a43d495
diff --git a/Android.bp b/Android.bp
index 22581b0..2f6fc20 100644
--- a/Android.bp
+++ b/Android.bp
@@ -54,7 +54,7 @@
             cfgs: ["llpvm_changes"],
         },
         release_avf_enable_multi_tenant_microdroid_vm: {
-            cfgs: ["payload_not_root"],
+            cfgs: ["multi_tenant"],
         },
         release_avf_enable_remote_attestation: {
             cfgs: ["remote_attestation"],