Add pr-review e2e test and speed up e2e tests (#37345)

- add pr-review e2e test
- speed up most tests by logging in via POST to avoid the login form,
login form is still exercised in a dedicated test
- speed up most tests be removing post-test cleanup, unnecessary because
each repo is created with a unique name
- misc parallelization and api call reduction
- total suite runtime is about the same as before

---------

Co-authored-by: Claude (Opus 4.7) <noreply@anthropic.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

tests/e2e/readme.test.ts

@@ -1,11 +1,10 @@
 import {env} from 'node:process';
 import {test, expect} from '@playwright/test';
-import {apiCreateRepo, apiDeleteRepo, randomString} from './utils.ts';
+import {apiCreateRepo, randomString} from './utils.ts';
 
 test('repo readme', async ({page}) => {
   const repoName = `e2e-readme-${randomString(8)}`;
   await apiCreateRepo(page.request, {name: repoName});
   await page.goto(`/${env.GITEA_TEST_E2E_USER}/${repoName}`);
   await expect(page.locator('#readme')).toContainText(repoName);
-  await apiDeleteRepo(page.request, env.GITEA_TEST_E2E_USER, repoName);
 });