Merge in 'release/3.1' changes

Author: dotnet-bot

eng/platform-matrix.yml

@@ -170,15 +170,9 @@ jobs:
       osGroup: OSX
       osIdentifier: OSX
       helixQueues:
-      - ${{ if and(eq(variables['System.TeamProject'], 'public'), in(parameters.helixQueueGroup, 'pr', 'ci', 'corefx')) }}:
-        - OSX.1013.Amd64.Open
       - ${{ if and(eq(variables['System.TeamProject'], 'public'), notIn(parameters.helixQueueGroup, 'pr', 'ci', 'corefx')) }}:
-        - OSX.1012.Amd64.Open
-        - OSX.1013.Amd64.Open
         - OSX.1014.Amd64.Open
       - ${{ if eq(variables['System.TeamProject'], 'internal') }}:
-        - OSX.1012.Amd64
-        - OSX.1013.Amd64
         - OSX.1014.Amd64
       ${{ insert }}: ${{ parameters.jobParameters }}