Update Android vulkan_content_browsertests

A recent change to support mixed Vulkan implementation and GrContext
led to requiring an additional flag to enable Vulkan as the GrContext.

It looks like one test suite was missed in that update.

TEST=vulkan_content_browsertest

Change-Id: I6474e113d45d3854edd67ec704a6704161585a3f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1901800
Auto-Submit: Jonathan Ross <jonross@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Reviewed-by: Aaron Gable <agable@chromium.org>
Commit-Queue: Jonathan Ross <jonross@chromium.org>
Cr-Commit-Position: refs/heads/master@{#713846}

testing/buildbot/chromium.gpu.fyi.json

@@ -6752,6 +6752,7 @@
       {
         "args": [
           "--use-vulkan=native",
+          "--gr-context-type=vulkan",
           "--disable-vulkan-fallback-to-gl-for-testing",
           "--enable-features=UseSkiaRenderer",
           "--test-launcher-filter-file=../../testing/buildbot/filters/gpu.skiarenderer_vulkan_content_browsertests.filter",

testing/buildbot/test_suites.pyl

@@ -3862,6 +3862,7 @@
       'vulkan_content_browsertests': {
         'args': [
           '--use-vulkan=native',
+          '--gr-context-type=vulkan',
           '--disable-vulkan-fallback-to-gl-for-testing',
           '--enable-features=UseSkiaRenderer',
           '--test-launcher-filter-file=../../testing/buildbot/filters/gpu.skiarenderer_vulkan_content_browsertests.filter',