[devtools] Filter layout tests to include only devtools relevant tests

Land only after a confirmation of successful run of devtools_frontend_linux_blink_light_rel bot.
https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/1916899

Bug: chromium:1018204
Change-Id: I42bde537652bdf445d74788fb5e6764cabe5d960
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1916466
Commit-Queue: Michael Achenbach <[email protected]>
Reviewed-by: John Budorick <[email protected]>
Reviewed-by: Michael Achenbach <[email protected]>
Cr-Commit-Position: refs/heads/master@{#715663}
diff --git a/testing/buildbot/test_suite_exceptions.pyl b/testing/buildbot/test_suite_exceptions.pyl
index 61e8081..4fb8158 100644
--- a/testing/buildbot/test_suite_exceptions.pyl
+++ b/testing/buildbot/test_suite_exceptions.pyl
@@ -1880,6 +1880,14 @@
       'Win10 Tests x64 (dbg)',
     ],
     'modifications': {
+      'devtools_frontend_linux_blink_light_rel': {
+        'args': [
+          'http/tests/devtools',
+        ],
+        'swarming': {
+          'shards': 4,
+        },
+      },
       # chromium.fyi
       'fuchsia-fyi-x64-rel': {
         'args': [