[test resources] Fix regression - base name overrides in CI (#5924)

This PR fixes an issue introduced in #5242 which stopped respecting BaseName parameter overrides in CI mode. This caused issues in stress deployments where we intentionally override BaseName to get a short name hash and need the value to match up with other places where inject it.

CC @richardpark-msft @lmolkova

eng/common/TestResources/SubConfig-Helpers.ps1

@@ -23,6 +23,12 @@ function GetBaseAndResourceGroupNames(
     [string]$serviceDirectoryName,
     [bool]$CI
 ) {
+    if ($baseNameDefault) {
+        $base = $baseNameDefault.ToLowerInvariant()
+        $group = $resourceGroupNameDefault ? $resourceGroupNameDefault : ("rg-$baseNameDefault".ToLowerInvariant())
+        return $base, $group
+    }
+
     if ($CI) {
         $base = 't' + (New-Guid).ToString('n').Substring(0, 16)
         # Format the resource group name based on resource group naming recommendations and limitations.
@@ -37,12 +43,6 @@ function GetBaseAndResourceGroupNames(
         return $base, $group
     }
 
-    if ($baseNameDefault) {
-        $base = $baseNameDefault.ToLowerInvariant()
-        $group = $resourceGroupNameDefault ? $resourceGroupNameDefault : ("rg-$baseNameDefault".ToLowerInvariant())
-        return $base, $group
-    }
-
     # Handle service directories in nested directories, e.g. `data/aztables`
     $serviceDirectorySafeName = $serviceDirectoryName -replace '[\./\\]', ''
     # Seed off resource group name if set to avoid name conflicts with deployments where it is not set