Fix unstable E2E tests on CI

[wk9874]

Describe the bug
On the CI, the tests are unstable. Especially these two:

FAILED tests/end_to_end/test_samples_page.py::test_create_samples_shot_data_file[chromium] - AssertionError: Locator expected to contain text '12380'
Actual value: None
Error: element(s) not found 
Call log:
  - Expect "to_contain_text" with timeout 5000ms
  - waiting for get_by_role("row").nth(1)

FAILED tests/end_to_end/test_sample_view_page.py::test_save_on_navigate[chromium-Previous-True-2] - playwright._impl._errors.TimeoutError: Locator.click: Timeout 30000ms exceeded.
Call log:
  - waiting for get_by_role("menuitem", name="Add Time Point")