Sync eng/common directory with azure-sdk-tools for PR 2578 (Azure#26544)

* excluding duplicated env:USER in image tag

* NIT

* removing default repo name

Co-authored-by: Albert Cheng <albertcheng@microsoft.com>

Author: azure-sdk

eng/common/scripts/stress-testing/stress-test-deployment-lib.ps1

@@ -86,12 +86,6 @@ function DeployStressTests(
         $subscription = 'Azure SDK Test Resources'
     }
 
-    if (!$repository) {
-        $repository = if ($env:USER) { $env:USER } else { "${env:USERNAME}" }
-        # Remove spaces, etc. that may be in $namespace
-        $repository -replace '\W'
-    }
-
     if ($login) {
         if (!$clusterGroup -or !$subscription) {
             throw "clusterGroup and subscription parameters must be specified when logging into an environment that is not test or prod."