Test suite: Fix set_browser_url

It happened that the 3 second timeouts of the try_for(3) blocks were exceeded by browser_url_entry:

02:38:58.611529615: executing Python as amnesia:
    nodes3887 = node3886.findChildren(dogtail.predicate.GenericPredicate(roleName=r'tool bar'))
    print(len(nodes3887))
02:38:59.583862975: retry_action: Operation failed with exception: Timeout::Error: try_for() timeout expired

and then shortly after, the response of the findChildren() call is received but dropped:

02:39:00.035361193: Dropped out-of-order remote shell response: got id 11285 but expected id 11286

The fix is to avoid the 3 second timeouts and just let the calls to browser_url_entry take as long as they need.

Closes #20357 (closed)