fix: allow for tracked time to be removed again (#8575)

- `getElementById` requires a id to be passed and not a query selector, change it to `querySelector`.
- Regression of forgejo/forgejo#7408
- Resolves forgejo/forgejo#8571
- Add E2E tests for adding manual tracked time and removing it.

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/8575
Reviewed-by: Otto <otto@codeberg.org>
Reviewed-by: 0ko <0ko@noreply.codeberg.org>
Co-authored-by: Gusted <postmaster@gusted.xyz>
Co-committed-by: Gusted <postmaster@gusted.xyz>

web_src/js/features/repo-issue.js

@@ -57,7 +57,7 @@ export function initRepoIssueTimeTracking() {
     $(sel).modal({
       duration: 200,
       onApprove() {
-        document.getElementById(`${sel} form`).requestSubmit();
+        document.querySelector(`${sel} form`).requestSubmit();
       },
     }).modal('show');
   });