Switch GPU.FYI Pixel 2 bots to use PQ3A Chrome pool

Android FYI Release (Pixel 2)
Android FYI SkiaRenderer Vulkan (Pixel 2)

were using PQ2A Chrome-GPU pool before.

TBR=kbr, bpastene

Bug: 1006006
Change-Id: Id80aff4d23509fdeea41099555b6492def9d16ea
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1817202Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Reviewed-by: Ben Pastene <bpastene@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Yuly Novikov <ynovikov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#698947}

testing/buildbot/chromium.gpu.fyi.json

@@ -6680,11 +6680,11 @@
           "containment_type": "AUTO",
           "dimension_sets": [
             {
-              "device_os": "P",
+              "device_os": "PQ3A.190801.002",
+              "device_os_flavor": "google",
               "device_os_type": "userdebug",
               "device_type": "walleye",
-              "os": "Android",
-              "pool": "Chrome-GPU"
+              "os": "Android"
             }
           ],
           "idempotent": false,
@@ -6713,11 +6713,11 @@
           "containment_type": "AUTO",
           "dimension_sets": [
             {
-              "device_os": "P",
+              "device_os": "PQ3A.190801.002",
+              "device_os_flavor": "google",
               "device_os_type": "userdebug",
               "device_type": "walleye",
-              "os": "Android",
-              "pool": "Chrome-GPU"
+              "os": "Android"
             }
           ],
           "idempotent": false
@@ -6746,11 +6746,11 @@
           "containment_type": "AUTO",
           "dimension_sets": [
             {
-              "device_os": "P",
+              "device_os": "PQ3A.190801.002",
+              "device_os_flavor": "google",
               "device_os_type": "userdebug",
               "device_type": "walleye",
-              "os": "Android",
-              "pool": "Chrome-GPU"
+              "os": "Android"
             }
           ],
           "idempotent": false,
@@ -6780,11 +6780,11 @@
           "containment_type": "AUTO",
           "dimension_sets": [
             {
-              "device_os": "P",
+              "device_os": "PQ3A.190801.002",
+              "device_os_flavor": "google",
               "device_os_type": "userdebug",
               "device_type": "walleye",
-              "os": "Android",
-              "pool": "Chrome-GPU"
+              "os": "Android"
             }
           ],
           "idempotent": false,
@@ -7060,11 +7060,11 @@
           "containment_type": "AUTO",
           "dimension_sets": [
             {
-              "device_os": "P",
+              "device_os": "PQ3A.190801.002",
+              "device_os_flavor": "google",
               "device_os_type": "userdebug",
               "device_type": "walleye",
-              "os": "Android",
-              "pool": "Chrome-GPU"
+              "os": "Android"
             }
           ],
           "output_links": [
@@ -7119,11 +7119,11 @@
           "containment_type": "AUTO",
           "dimension_sets": [
             {
-              "device_os": "P",
+              "device_os": "PQ3A.190801.002",
+              "device_os_flavor": "google",
               "device_os_type": "userdebug",
               "device_type": "walleye",
-              "os": "Android",
-              "pool": "Chrome-GPU"
+              "os": "Android"
             }
           ],
           "idempotent": false,

testing/buildbot/mixins.pyl

@@ -545,13 +545,6 @@
       },
     },
   },
-  'pie': {
-    'swarming': {
-      'dimensions': {
-        'device_os': 'P',
-      },
-    },
-  },
   'pie-x86-emulator': {
     '$mixin_append': {
       'args': [

testing/buildbot/waterfalls.pyl

@@ -2574,8 +2574,7 @@
         'os_type': 'android',
         'skip_merge_script': True,
         'mixins': [
-          'gpu_pool',
-          'pie',
+          'pie_fleet',
           'walleye',
         ],
         'test_suites': {
@@ -2601,8 +2600,7 @@
         'browser_config': 'android-chromium',
         'skip_merge_script': True,
         'mixins': [
-          'gpu_pool',
-          'pie',
+          'pie_fleet',
           'walleye',
         ],
         'test_suites': {