test(api): fix test for empty categories

The application allows adding empty categories. The test cannot be
executed in a shared env because it would fail the second tie is
executed becuase the category already exists.

tests/e2e/contexts/category/contract.rs

@@ -111,6 +111,13 @@ async fn it_should_allow_adding_empty_categories() {
     let mut env = TestEnv::new();
     env.start(api::Implementation::ActixWeb).await;
 
+    if env.is_shared() {
+        // This test cannot be run in a shared test env because it will fail
+        // when the empty category already exits
+        println!("Skipped");
+        return;
+    }
+
     let logged_in_admin = new_logged_in_admin(&env).await;
     let client = Client::authenticated(&env.server_socket_addr().unwrap(), &logged_in_admin.token);
 
@@ -342,6 +349,13 @@ mod with_axum_implementation {
         let mut env = TestEnv::new();
         env.start(api::Implementation::Axum).await;
 
+        if env.is_shared() {
+            // This test cannot be run in a shared test env because it will fail
+            // when the empty category already exits
+            println!("Skipped");
+            return;
+        }
+
         if env::var(ENV_VAR_E2E_EXCLUDE_AXUM_IMPL).is_ok() {
             println!("Skipped");
             return;