Don't run angle_end2end_tests with SwiftShader backend on GPU bots.

Since we have SwANGLE bots now to run these, we can offload the GPU bots.
Also, possibly reduce the flakiness on them due to anglebug.com/4396.

Bug: 1007018
Change-Id: I3023bfb163804fe5aacb0d8a0fa93523b757feda
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2132945Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Yuly Novikov <ynovikov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#755977}

testing/buildbot/test_suites.pyl

@@ -1674,6 +1674,7 @@
           # http://crbug.com/669196
           '--test-launcher-retry-limit=0',
           '--test-launcher-batch-limit=256',
+          '--gtest_filter=-*Vulkan_SwiftShader*',
         ],
         'linux_args': ['--no-xvfb'],
         'should_retry_with_patch': False,