infra: register "GPU Mac Builder" and its testers in LUCI UI.

Testers:
 * "Mac Release (Intel)"
 * "Mac Retina Release (AMD)"

R=kbr@chromium.org

Bug: 790063,790077,790066
Change-Id: Id7bdaa570abd2bae90051d6389f24a1f66426ed4
No-Try: True
Reviewed-on: https://chromium-review.googlesource.com/994534
Commit-Queue: Andrii Shyshkalov <tandrii@chromium.org>
Reviewed-by: Ryan Tseng <hinoka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547913}

infra/config/global/luci-milo.cfg

@@ -1892,6 +1892,39 @@ consoles: {
     category: "tester|10.13"
     short_name: "old"
   }
+
+  builders: {
+    name: "buildbucket/luci.chromium.ci/GPU Mac Builder"
+    category: "gpu|builder"
+    short_name: "new"
+  }
+  builders: {
+    name: "buildbot/chromium.gpu/GPU Mac Builder"
+    category: "gpu|builder"
+    short_name: "old"
+  }
+
+  builders: {
+    name: "buildbucket/luci.chromium.ci/Mac Release (Intel)"
+    category: "gpu|tester|intel"
+    short_name: "new"
+  }
+  builders: {
+    name: "buildbot/chromium.gpu/Mac Release (Intel)"
+    category: "gpu|tester|intel"
+    short_name: "old"
+  }
+
+  builders: {
+    name: "buildbucket/luci.chromium.ci/Mac Retina Release (AMD)"
+    category: "gpu|tester|amd"
+    short_name: "new"
+  }
+  builders: {
+    name: "buildbot/chromium.gpu/Mac Retina Release (AMD)"
+    category: "gpu|tester|amd"
+    short_name: "old"
+  }
 }
 
 # Everything below was generated from buildermap.json.
@@ -2892,6 +2925,7 @@ consoles: {
   }
   builders: {
     name: "buildbot/chromium.gpu/GPU Mac Builder"
+    name: "buildbucket/luci.chromium.ci/GPU Mac Builder"
     category: "Mac"
   }
   builders: {
@@ -2904,6 +2938,7 @@ consoles: {
   }
   builders: {
     name: "buildbot/chromium.gpu/Mac Release (Intel)"
+    name: "buildbucket/luci.chromium.ci/Mac Release (Intel)"
     category: "Mac"
   }
   builders: {
@@ -2912,6 +2947,7 @@ consoles: {
   }
   builders: {
     name: "buildbot/chromium.gpu/Mac Retina Release (AMD)"
+    name: "buildbucket/luci.chromium.ci/Mac Retina Release (AMD)"
     category: "Mac"
   }
   builders: {