tests(e2e): Refactor various tests

Goals:

- speedup
- less flakiness
- best practices and more use
- documentation

config:
- sync ports in Makefile and playwright config
  (otherwise, some tests fail locally because they assert the full URL including the (wrong) port)
- even more generous timeouts
- limit workers to one again (because I finally understand how
  Playwright works)
- allow nested functions to group them together with the related test

all:

- deprecate waitForLoadState('networkidle')
  - it is discouraged as per https://playwright.dev/docs/api/class-page#page-wait-for-load-state
  - I could not find a usage that seems to require it actually (see
    added documentation in README)
  - adding an exception should be made explicitly
  - it does not do what you might expect anyway in most cases
- only log in when necessary

webauthn:

- verify that login is possible after disabling key
- otherwise, the cleanup was not necessary after the previous refactor to create a fresh user each

issue-sidebar / WIP toggle:

- split into smaller chunks
- restore original state first
- add missed assertion to fix race condition (not waiting
  before state was reached)
- explicitly toggle the state to detect mismatch earlier

issue-sidebar / labels:

- restore original state first
- better waiting for background request

tests/e2e/actions.test.e2e.ts

@@ -44,7 +44,6 @@ test('workflow dispatch error: missing inputs', async ({browser}, workerInfo) =>
   const page = await context.newPage();
 
   await page.goto('/user2/test_workflows/actions?workflow=test-dispatch.yml&actor=0&status=0');
-  await page.waitForLoadState('networkidle');
 
   await page.locator('#workflow_dispatch_dropdown>button').click();
 
@@ -55,7 +54,6 @@ test('workflow dispatch error: missing inputs', async ({browser}, workerInfo) =>
   });
 
   await page.locator('#workflow-dispatch-submit').click();
-  await page.waitForLoadState('networkidle');
 
   await expect(page.getByText('Require value for input "String w/o. default".')).toBeVisible();
 });
@@ -68,13 +66,11 @@ test('workflow dispatch success', async ({browser}, workerInfo) => {
   const page = await context.newPage();
 
   await page.goto('/user2/test_workflows/actions?workflow=test-dispatch.yml&actor=0&status=0');
-  await page.waitForLoadState('networkidle');
 
   await page.locator('#workflow_dispatch_dropdown>button').click();
 
   await page.type('input[name="inputs[string2]"]', 'abc');
   await page.locator('#workflow-dispatch-submit').click();
-  await page.waitForLoadState('networkidle');
 
   await expect(page.getByText('Workflow run was successfully requested.')).toBeVisible();
 
@@ -83,7 +79,6 @@ test('workflow dispatch success', async ({browser}, workerInfo) => {
 
 test('workflow dispatch box not available for unauthenticated users', async ({page}) => {
   await page.goto('/user2/test_workflows/actions?workflow=test-dispatch.yml&actor=0&status=0');
-  await page.waitForLoadState('networkidle');
 
   await expect(page.locator('body')).not.toContainText(workflow_trigger_notification_text);
 });