Isolate model-specific Rust E2E tests

Keep model-catalog-dependent tests on dedicated clients, correct provider group teardown accounting, and discard shared connection state after any failed test.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: SteveSandersonMS

rust/tests/e2e/multi_provider_registry.rs

@@ -240,4 +240,4 @@ async fn should_route_delta_turbo_turn_to_its_provider_and_wire_model() {
     )
     .await;
 }
-static E2E: super::support::SharedE2eGroup = super::support::SharedE2eGroup::standard(CATEGORY, 2);
+static E2E: super::support::SharedE2eGroup = super::support::SharedE2eGroup::standard(CATEGORY, 4);

rust/tests/e2e/rpc_session_state.rs

@@ -54,7 +54,7 @@ async fn should_call_session_rpc_model_getcurrent() {
 
 #[tokio::test]
 async fn should_call_session_rpc_model_switchto() {
-    super::support::with_shared_e2e_context(
+    super::support::with_dedicated_group_e2e_context(
         &E2E,
         "rpc_session_state",
         "should_call_session_rpc_model_switchto",
@@ -1207,4 +1207,4 @@ fn assistant_message_content_if_present(
     }
 }
 static E2E: super::support::SharedE2eGroup =
-    super::support::SharedE2eGroup::standard("rpc_session_state", 23);
+    super::support::SharedE2eGroup::standard("rpc_session_state", 22);

rust/tests/e2e/session.rs

@@ -1002,7 +1002,7 @@ async fn should_set_model_on_existing_session() {
 
 #[tokio::test]
 async fn should_set_model_with_reasoningeffort() {
-    super::support::with_shared_e2e_context(
+    super::support::with_dedicated_group_e2e_context(
         &E2E,
         "session",
         "should_set_model_with_reasoningeffort",
@@ -1752,4 +1752,4 @@ fn secret_number_tool() -> Tool {
         .with_handler(Arc::new(SecretNumberTool))
 }
 static E2E: super::support::SharedE2eGroup =
-    super::support::SharedE2eGroup::standard("session", 31);
+    super::support::SharedE2eGroup::standard("session", 30);

rust/tests/e2e/support.rs

@@ -223,8 +223,10 @@ pub async fn with_shared_e2e_context<F>(
         (result, cleanup_result)
     };
 
+    let test_succeeded = matches!(&result, Ok(Ok(Ok(()))));
     let completed = group.completed_invocations.fetch_add(1, Ordering::Relaxed) + 1;
-    let teardown_result = if cleanup_result.is_err()
+    let teardown_result = if !test_succeeded
+        || cleanup_result.is_err()
         || is_filtered_test_run()
         || completed == group.expected_invocations
     {