[Sheriff] Fix --gtest_filter argument for EA SWA tests

TBR=jomag@chromium.org,martiniss@chromium.org

Fixed: 1130984
Bug: 1094203
Change-Id: Ib109934adddbe514f4141ab78988c31ccc200aec
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2423715
Commit-Queue: Roman Sorokin [CET] <rsorokin@chromium.org>
Reviewed-by: Roman Sorokin [CET] <rsorokin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#809287}

testing/buildbot/chrome.ci.json

@@ -3680,7 +3680,7 @@
     "gtest_tests": [
       {
         "args": [
-          "--gtest-filter=*HelpApp*:*MediaApp*"
+          "--gtest_filter=*HelpApp*:*MediaApp*"
         ],
         "merge": {
           "args": [],

testing/buildbot/chrome.json

@@ -2879,7 +2879,7 @@
     "gtest_tests": [
       {
         "args": [
-          "--gtest-filter=*HelpApp*:*MediaApp*"
+          "--gtest_filter=*HelpApp*:*MediaApp*"
         ],
         "merge": {
           "args": [],

testing/buildbot/test_suites.pyl

@@ -1238,7 +1238,7 @@
     'easwa_browser_tests' : {
       'easwa_browser_tests': {
         'args': [
-          '--gtest-filter=*HelpApp*:*MediaApp*'
+          '--gtest_filter=*HelpApp*:*MediaApp*'
         ],
         'swarming': {
           'shards': 1,