change "special url" in tests to avoid vulkan error

On GH actions I'm seeing an "unexpected line" failure around creating a
vulkan context when loading chrome://gpu

    ERROR tests/end2end/features/test_tabs_bdd.py::test_cloning_a_tab_with_a_special_url - end2end.fixtures.testprocess.InvalidLine:
    1829
    Error: vkCreateInstance failed with VK_ERROR_INCOMPATIBLE_DRIVER
    1830
        at CheckVkSuccessImpl (../../../3rdparty/chromium/third_party/dawn/src/dawn/native/vulkan/VulkanError.cpp:88)
    1831
        at CreateVkInstance (../../../3rdparty/chromium/third_party/dawn/src/dawn/native/vulkan/BackendVk.cpp:360)
    1832
        at Initialize (../../../3rdparty/chromium/third_party/dawn/src/dawn/native/vulkan/BackendVk.cpp:235)
    1833
        at Create (../../../3rdparty/chromium/third_party/dawn/src/dawn/native/vulkan/BackendVk.cpp:165)
    1834
        at operator() (../../../3rdparty/chromium/third_party/dawn/src/dawn/native/vulkan/BackendVk.cpp:420)

I'm not sure its actually failing the test, we are just seeing the error
in the logs and flagging it.
Instead of adding the logs to an ignore list I'm going to switch the
page we use so that if the error comes up for real we'll be sure to see
the logs.

tests/end2end/features/tabs.feature

@@ -782,7 +782,7 @@ Feature: Tab management
 
     @qtwebkit_skip
     Scenario: Cloning a tab with a special URL
-        When I open chrome://gpu
+        When I open chrome://sandbox/
         And I run :tab-clone
         Then no crash should happen