Add sleep before deleting dummy_primitive to wait the redirect finishes

[Dawei-Pang]

The followed traceback is reported during SLES15.4/5/6/7 HAWK testing, please refer to https://jira.suse.com/browse/TEAM-11517 for details.

  File "/hawk_test.py", line 188, in <module>
    sys.exit(main())
             ~~~~^^
  File "/hawk_test.py", line 157, in main
    browser.test('test_delete_primitive', results) 
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 
  File "/hawk_test_driver.py", line 340, in test 
    if getattr(self, testname)(*extra):
       ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^
  File "/hawk_test_driver.py", line 808, in test_delete_primitive
    commit_btn.click()
    ~~~~~~~~~~~~~~~~^^
  File "/usr/lib64/python3.13/site-packages/selenium/webdriver/remote/webelement.py", line 94, in click
    self._execute(Command.CLICK_ELEMENT)
    ~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib64/python3.13/site-packages/selenium/webdriver/remote/webelement.py", line 395, in _execute
    return self._parent.execute(command, params) 
           ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
  File "/usr/lib64/python3.13/site-packages/selenium/webdriver/remote/webdriver.py", line 354, in execute
    self.error_handler.check_response(response)           
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^  
  File "/usr/lib64/python3.13/site-packages/selenium/webdriver/remote/errorhandler.py", line 229, in check_response
    raise exception_class(message, screen, stacktrace)

Add sleep before action to wait the previous redirect finishes.

VR:
15.4 https://openqa.suse.de/tests/24187545
15.5 https://openqa.suse.de/tests/24187542
15.6 https://openqa.suse.de/tests/24187538
15.7 https://openqa.suse.de/tests/24187524
12.5 https://openqa.suse.de/tests/24187548

3 times of verification with above releases are PASS.

[lilyeyes]

LGTM.