Allow default matrix selection override (#23659)

Co-authored-by: Ben Broderick Phillips <bebroder@microsoft.com>

eng/common/scripts/stress-testing/find-all-stress-packages.ps1

@@ -48,11 +48,21 @@ function FindStressPackages(
 
         VerifyAddonsVersion $chart $chartFile
 
+        # Default to "sparse" matrix selection type, unless a default is specified
+        # in Chart.yaml annotations, or an override is passed in from the command line
+        $selection = if ($MatrixSelection) {
+            $MatrixSelection
+        } elseif ($chart['annotations'] -and $chart['annotations']['matrixSelection']) {
+            $chart['annotations']['matrixSelection']
+        } else {
+            "sparse"
+        }
+
         $matrixFilePath = (Join-Path $chartFile.Directory.FullName $MatrixFileName)
         if (Test-Path $matrixFilePath) {
             GenerateScenarioMatrix `
                 -matrixFilePath $matrixFilePath `
-                -Selection $MatrixSelection `
+                -Selection $selection `
                 -DisplayNameFilter $MatrixDisplayNameFilter `
                 -Filters $MatrixFilters `
                 -Replace $MatrixReplace `

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

@@ -103,7 +103,7 @@ function DeployStressTests(
     [Parameter(Mandatory=$False)][switch]$Template,
     [Parameter(Mandatory=$False)][switch]$RetryFailedTests,
     [Parameter(Mandatory=$False)][string]$MatrixFileName,
-    [Parameter(Mandatory=$False)][string]$MatrixSelection = "sparse",
+    [Parameter(Mandatory=$False)][string]$MatrixSelection,
     [Parameter(Mandatory=$False)][string]$MatrixDisplayNameFilter,
     [Parameter(Mandatory=$False)][array]$MatrixFilters,
     [Parameter(Mandatory=$False)][array]$MatrixReplace,