ci(azure-pipelines): move pool definition to stage level

.azure-pipelines/templates/service.yaml

@@ -31,11 +31,11 @@ parameters:
 
 stages:
   - stage: ${{ parameters.serviceName }}
+    pool: '${{ parameters.servicePool }}'
     jobs:
     - job: ImageBuild_${{parameters.serviceName}}
       displayName: Build ${{parameters.serviceName}} image
       condition: or(eq(variables.forcePushLatest, true), eq(variables.onMasterBranch, true), eq(variables.onUpdateBranch, true))
-      pool: '${{ parameters.servicePool }}'
       timeoutInMinutes: ${{ parameters.serviceTimeout }}
       container:
         image: devfra.azurecr.io/de.fraport.build/tools:1.1.0
@@ -94,7 +94,6 @@ stages:
       dependsOn:
         - ImageBuild_${{parameters.serviceName}}
       condition: in(dependencies.ImageBuild_${{parameters.serviceName}}.result, 'Succeeded', 'Skipped')
-      pool: '${{ parameters.servicePool }}'
       container:
         # TODO: use BuildNumber instead of latest in update branches
         # image: devfra.azurecr.io/de.fraport.fradrive.build/frontend:$(Build.BuildNumber)