Make rpc_subscriptions.rs tests serial (#9556)

automerge

(cherry picked from commit b58338b066)

core/src/rpc_subscriptions.rs

@@ -622,6 +622,7 @@ pub(crate) mod tests {
     };
     use jsonrpc_core::futures::{self, stream::Stream};
     use jsonrpc_pubsub::typed::Subscriber;
+    use serial_test_derive::serial;
     use solana_budget_program;
     use solana_sdk::{
         signature::{Keypair, Signer},
@@ -656,6 +657,7 @@ pub(crate) mod tests {
     }
 
     #[test]
+    #[serial]
     fn test_check_account_subscribe() {
         let GenesisConfigInfo {
             genesis_config,
@@ -728,6 +730,7 @@ pub(crate) mod tests {
     }
 
     #[test]
+    #[serial]
     fn test_check_program_subscribe() {
         let GenesisConfigInfo {
             genesis_config,
@@ -808,6 +811,7 @@ pub(crate) mod tests {
     }
 
     #[test]
+    #[serial]
     fn test_check_signature_subscribe() {
         let GenesisConfigInfo {
             genesis_config,
@@ -949,6 +953,7 @@ pub(crate) mod tests {
     }
 
     #[test]
+    #[serial]
     fn test_check_slot_subscribe() {
         let (subscriber, _id_receiver, transport_receiver) =
             Subscriber::new_test("slotNotification");
@@ -990,6 +995,7 @@ pub(crate) mod tests {
     }
 
     #[test]
+    #[serial]
     fn test_check_root_subscribe() {
         let (subscriber, _id_receiver, mut transport_receiver) =
             Subscriber::new_test("rootNotification");
@@ -1030,6 +1036,7 @@ pub(crate) mod tests {
     }
 
     #[test]
+    #[serial]
     fn test_add_and_remove_subscription() {
         let mut subscriptions: HashMap<u64, HashMap<SubscriptionId, (Sink<()>, Confirmations)>> =
             HashMap::new();