Remove athena targets

fyi and chromium_athena.json will be removed in separate CL

BUG=448472

Review URL: https://codereview.chromium.org/851743005

Cr-Commit-Position: refs/heads/master@{#311533}

testing/buildbot/chromium.chromiumos.json

@@ -86,7 +86,6 @@
       },
       "sql_unittests",
       "nacl_loader_unittests",
-      "athena_unittests",
       "app_shell_browsertests",
       "app_shell_unittests",
       "chromevox_tests",
@@ -100,7 +99,6 @@
       "app_shell_browsertests",
       "app_shell_unittests",
       "ash_unittests",
-      "athena_unittests",
       "aura_unittests",
       "base_unittests",
       "cacheinvalidation_unittests",
@@ -250,7 +248,6 @@
           "shards": 2
         }
       },
-      "athena_unittests",
       "gcm_unit_tests",
       "skia_unittests",
       {

testing/buildbot/chromium.memory.json

@@ -233,7 +233,6 @@
           "can_use_on_swarming_builders": true
         }
       },
-      "athena_unittests",
       "aura_unittests",
       {
         "test": "base_unittests",

testing/buildbot/chromium.webkit.json

@@ -83,7 +83,6 @@
       },
       "sql_unittests",
       "nacl_loader_unittests",
-      "athena_unittests",
       "app_shell_browsertests",
       "app_shell_unittests",
       "chromevox_tests",
@@ -173,7 +172,6 @@
           "shards": 2
         }
       },
-      "athena_unittests",
       "gcm_unit_tests",
       "skia_unittests",
       {

testing/buildbot/chromium_trybot.json

@@ -250,15 +250,6 @@
         "chromium_chromeos_ozone"
       ]
     },
-    {
-      "test": "athena_unittests",
-      "platforms": ["linux"],
-      "chromium_configs": [
-        "chromium_chromeos",
-        "chromium_chromeos_athena",
-        "chromium_chromeos_ozone"
-      ]
-    },
     {
       "test": "display_unittests",
       "platforms": ["linux"]