Add infra configs for "try-nougat-phone-tester" trybot.

Bug: 879704
No-Try: True
Change-Id: I454192e7c0cde3883bfe43e76029727b4924bfc1
Reviewed-on: https://chromium-review.googlesource.com/1200312
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#588208}

infra/config/global/cr-buildbucket.cfg

@@ -2609,6 +2609,10 @@ buckets {
       mixins: "android-gpu-manual-try"
       name: "gpu-manual-try-android-p-pixel-2-64-deqp"
     }
+    builders {
+      mixins: "android-try"
+      name: "try-nougat-phone-tester"
+    }
 
     builders { mixins: "chromeos-try" name: "chromeos-amd64-generic-rel" }
     builders { mixins: "chromeos-try" name: "chromeos-daisy-rel" }

infra/config/global/luci-milo.cfg

@@ -4015,6 +4015,9 @@ consoles {
   builders {
     name: "buildbucket/luci.chromium.try/gpu-manual-try-android-p-pixel-2-64-deqp"
   }
+  builders {
+    name: "buildbucket/luci.chromium.try/try-nougat-phone-tester"
+  }
   builder_view_only: true
 }
 
@@ -4758,6 +4761,9 @@ consoles {
   builders {
     name: "buildbucket/luci.chromium.try/mac_upload_clang"
   }
+  builders {
+    name: "buildbucket/luci.chromium.try/try-nougat-phone-tester"
+  }
   builders {
     name: "buildbucket/luci.chromium.try/win10_chromium_x64_dbg_ng"
   }

tools/mb/mb_config.pyl

@@ -567,6 +567,7 @@
       'gpu-manual-try-android-p-pixel-2-64': 'gpu_tests_android_vulkan_release_trybot_arm64',
       'gpu-manual-try-android-p-pixel-2-64-deqp': 'deqp_android_vulkan_release_trybot_arm64',
       'linux_android_dbg_ng': 'android_debug_trybot',
+      'try-nougat-phone-tester': 'android_debug_trybot_arm64',
     },
 
     # TODO(crbug/786044): Remove non-compile debug configs when migrated.