Solve the immediate problem

Manually clean up the messed up daemon state upon exit from
`test_establish_tunnel_without_api` using the ScopeGuard/defer pattern.

test/test-manager/src/tests/tunnel.rs

@@ -780,6 +780,17 @@ pub async fn test_establish_tunnel_without_api(
     rpc.stop_mullvad_daemon().await?;
     // 3
     let borked_env = [("MULLVAD_API_ADDR", "1.3.3.7:421")];
+    // 3.5 - Create a cleanup routine which resets the daemon's environment when the test is done.
+    let runtime_handle = tokio::runtime::Handle::try_current()?;
+    let mullvad_client_ = mullvad_client.clone();
+    scopeguard::defer! {
+        let _ = runtime_handle.block_on(helpers::restart_daemon_with(
+            &rpc,
+            &ctx,
+            mullvad_client_,
+            helpers::get_app_env(),
+        ));
+    };
     // 4
     log::debug!("Restarting the daemon with the following overrides: {borked_env:?}");
     let mut mullvad_client =