eng/platform-matrix.yml remove RedHat.6.Amd64 (#28212)

* remove redhat.6.amd64 from platform matrix yml.

* minor: platform-matrix.yml - removed extra space

Author: vseanreesermsft

eng/platform-matrix.yml

@@ -111,25 +111,6 @@ jobs:
       crossrootfsDir: '/crossrootfs/arm64'
       ${{ insert }}: ${{ parameters.jobParameters }}
 
-# Linux rhel6 x64
-
-- ${{ if or(containsValue(parameters.platforms, 'Linux_rhel6_x64'), eq(parameters.platformGroup, 'all')) }}:
-  - template: ${{ parameters.jobTemplate }}
-    parameters:
-      ignoreDependencyOnBuildJobs: ${{ parameters.ignoreDependencyOnBuildJobs }}
-      buildConfig: ${{ parameters.buildConfig }}
-      archType: x64
-      osGroup: Linux
-      osIdentifier: Linux_rhel6
-      container:
-        image: centos-6-3e800f1-20190501005338
-        registry: mcr
-      helixQueues:
-      # TODO: enable RedHat.6.Amd64.Open once https://github.com/dotnet/coreclr/issues/23580 is resolved
-      - ${{ if eq(variables['System.TeamProject'], 'internal') }}:
-        - RedHat.6.Amd64
-      ${{ insert }}: ${{ parameters.jobParameters }}
-
 # Linux x64
 
 - ${{ if or(containsValue(parameters.platforms, 'Linux_x64'), in(parameters.platformGroup, 'all', 'gcstress')) }}: