[Keyserver/rust] Remove legacy auth_token configuration

Summary:
Follow up to deprecating the old keyserver proxy service

Depends on D8402

Test Plan: N/A

Reviewers: varun

Reviewed By: varun

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D8404

keyserver/addons/rust-node-addon/src/identity_client/mod.rs

@@ -44,15 +44,13 @@ lazy_static! {
 #[serde(rename_all = "camelCase")]
 struct IdentityServiceConfig {
   identity_socket_addr: String,
-  identity_auth_token: String,
 }
 
 impl Default for IdentityServiceConfig {
   fn default() -> Self {
     info!("Using default identity configuration");
     Self {
       identity_socket_addr: "https://[::1]:50054".to_string(),
-      identity_auth_token: "test".to_string(),
     }
   }
 }