Use image.yml in docindex pipeline (Azure#41267)

* Use image.yml in docindex pipeline

* CODEOWNERS for docindex.yml

* LinuxImageDemand

Author: danieljurek

.github/CODEOWNERS

@@ -850,6 +850,7 @@
 /eng/pipelines/templates/jobs/tests-nightly-python.yml               @lmazuel @mccoyp
 /eng/pipelines/aggregate-reports.yml                                 @lmazuel @mccoyp @YalinLi0312 @kristapratico
 /eng/common/pipelines/codeowners-linter.yml                          @lmazuel @mccoyp
+/eng/pipelines/docindex.yml                                          @danieljurek @scbedd @weshaggard @benbp
 
 # Add approvers for typespec-python emitter version updates
 /eng/emitter-package.json                                            @mccoyp @catalinaperalta @kristapratico @iscai-msft

eng/pipelines/docindex.yml

@@ -21,13 +21,14 @@ parameters:
 
 variables:
   - template: /eng/pipelines/templates/variables/globals.yml
+  - template: /eng/pipelines/templates/variables/image.yml
 jobs:
   - template: /eng/common/pipelines/templates/jobs/docindex.yml
 
   - job: UpdateDocsMsBuildConfig
     pool:
-      name: azsdk-pool-mms-ubuntu-2004-general
-      vmImage: Ubuntu20.04
+      name: $(LINUXPOOL)
+      demands: $(LinuxImageDemand)
     variables:
       DocRepoLocation: $(Pipeline.Workspace)/docs
       DocRepoOwner: MicrosoftDocs

eng/pipelines/templates/variables/image.yml

@@ -25,3 +25,5 @@ variables:
   - name: MACOS
     value: macOS
 
+  - name: LinuxImageDemand
+    value: ImageOverride -equals $(LINUXVMIMAGE)