Update Azure queues for Linux and MacOS builds (#7231)

- aspnet/AspNetCore-Internal#1717
- use a specific Linux image

Author: dougbu

.azure/pipelines/jobs/default-build.yml

@@ -73,11 +73,17 @@ jobs:
     ${{ if ne(parameters.poolName, '') }}:
       name: ${{ parameters.poolName }}
     ${{ if and(eq(parameters.poolName, ''), eq(parameters.agentOs, 'macOS')) }}:
-      name: Hosted macOS
+      ${{ if eq(variables['System.TeamProject'], 'internal') }}:
+        name: Hosted Mac Internal
+      ${{ if ne(variables['System.TeamProject'], 'internal') }}:
+        name: Hosted macOS
       vmImage: macOS-10.13
     ${{ if and(eq(parameters.poolName, ''), eq(parameters.agentOs, 'Linux')) }}:
-      name: Hosted Ubuntu 1604
-      vmImage: ubuntu-16.04
+      ${{ if eq(variables['System.TeamProject'], 'internal') }}:
+        name: dnceng-linux-internal-temp
+      ${{ if ne(variables['System.TeamProject'], 'internal') }}:
+        name: dnceng-linux-external-temp
+      vmImage: Linux_Ubuntu_16.04
     ${{ if and(eq(parameters.poolName, ''), eq(parameters.agentOs, 'Windows')) }}:
       ${{ if eq(variables['System.TeamProject'], 'internal') }}:
         name: dotnet-internal-temp
@@ -160,4 +166,3 @@ jobs:
     - task: MicroBuildCleanup@1
       displayName: Cleanup MicroBuild tasks
       condition: always()
-