Deprecate put and return error in ILegacyKeystore

Legacy keystore is a old relic that was suppoed to be
disabled a while ago. It has enabled functionality that was
supposed to be removed but wasn't because it would break
changes in the VPN and WIFI code. This would begin the
process of permanently removing it.

Test: atest CtsKeystoreTestCases
Change-Id: Iedc1dca24a40eb0cf30c5280fc2842ff79cf7f17
diff --git a/keystore2/aconfig/flags.aconfig b/keystore2/aconfig/flags.aconfig
index 41e1a92..1ed1d9a 100644
--- a/keystore2/aconfig/flags.aconfig
+++ b/keystore2/aconfig/flags.aconfig
@@ -9,7 +9,7 @@
 }
 
 flag {
-  name: "disable_legacy_keystore_put"
+  name: "disable_legacy_keystore_put_v2"
   namespace: "hardware_backed_security"
   description: "This flag disables legacy keystore put and makes it so that command returns an error"
   bug: "307460850"