Update swarming dimension of tests in 'Android Nexus 5X Perf FYI' to mach swarming server migration

NOTRY=true  # tests are covered by PRESUBMIT only

Bug: 825181
Change-Id: I59ee1dc37b86d5100881c11789bbef2076b113ad
Reviewed-on: https://chromium-review.googlesource.com/995578Reviewed-by: Emily Hanley <eyaich@chromium.org>
Commit-Queue: Ned Nguyen <nednguyen@google.com>
Cr-Commit-Position: refs/heads/master@{#548062}

testing/buildbot/chromium.perf.fyi.json

@@ -64,8 +64,8 @@
           "can_use_on_swarming_builders": true,
           "dimension_sets": [
             {
-              "id": "build46-b1--device1",
-              "pool": "Chrome-perf-fyi"
+              "id": "build187-b7--device1",
+              "pool": "chrome.tests.perf-fyi"
             }
           ],
           "expiration": 3600,
@@ -88,8 +88,8 @@
           "can_use_on_swarming_builders": true,
           "dimension_sets": [
             {
-              "id": "build46-b1--device2",
-              "pool": "Chrome-perf-fyi"
+              "id": "build187-b7--device2",
+              "pool": "chrome.tests.perf-fyi"
             }
           ],
           "expiration": 3600,
@@ -112,8 +112,8 @@
           "can_use_on_swarming_builders": true,
           "dimension_sets": [
             {
-              "id": "build46-b1--device2",
-              "pool": "Chrome-perf-fyi"
+              "id": "build187-b7--device2",
+              "pool": "chrome.tests.perf-fyi"
             }
           ],
           "expiration": 3600,
@@ -136,8 +136,8 @@
           "can_use_on_swarming_builders": true,
           "dimension_sets": [
             {
-              "id": "build46-b1--device2",
-              "pool": "Chrome-perf-fyi"
+              "id": "build187-b7--device2",
+              "pool": "chrome.tests.perf-fyi"
             }
           ],
           "expiration": 3600,
@@ -163,8 +163,8 @@
           "can_use_on_swarming_builders": true,
           "dimension_sets": [
             {
-              "id": "build46-b1--device2",
-              "pool": "Chrome-perf-fyi"
+              "id": "build187-b7--device2",
+              "pool": "chrome.tests.perf-fyi"
             }
           ],
           "expiration": 3600,
@@ -190,8 +190,8 @@
           "can_use_on_swarming_builders": true,
           "dimension_sets": [
             {
-              "id": "build46-b1--device2",
-              "pool": "Chrome-perf-fyi"
+              "id": "build187-b7--device2",
+              "pool": "chrome.tests.perf-fyi"
             }
           ],
           "expiration": 3600,