refactor(plugins): harden target-plugin system and admin plugin contract (#4217)

crates/audit/src/system.rs

@@ -550,7 +550,6 @@ mod tests {
     use rustfs_targets::store::{Key, Store};
     use rustfs_targets::target::{EntityTarget, QueuedPayload, QueuedPayloadMeta};
     use rustfs_targets::{StoreError, Target, TargetError};
-    use serde::{Serialize, de::DeserializeOwned};
     use std::collections::HashMap;
     use std::sync::Arc;
     use std::sync::atomic::{AtomicUsize, Ordering};
@@ -574,7 +573,7 @@ mod tests {
     #[async_trait]
     impl<E> Target<E> for TestTarget
     where
-        E: Send + Sync + 'static + Clone + Serialize + DeserializeOwned,
+        E: rustfs_targets::PluginEvent,
     {
         fn id(&self) -> TargetID {
             self.id.clone()