Use the common Cosmos emulator template. (Azure#12678)

* Use the common Cosmos emulator template.

* Use absolute path.

Author: mitchdenny

eng/pipelines/templates/stages/cosmos-sdk-client.yml

@@ -41,7 +41,7 @@ stages:
           vmImage: $(OSVmImage)
 
         steps:
-          - template: ../steps/cosmos-emulator.yml
+          - template: /eng/common/pipelines/templates/steps/cosmos-emulator.yml
             parameters:
               EmulatorMsiUrl: ${{ parameters.EmulatorMsiUrl }}
               StartParameters: ${{ parameters.EmulatorStartParameters }}