Sync eng/common directory with azure-sdk-tools for PR 12061 (Azure#52595)

* bump proxy to one that includes our multipart/formdata fix
* update proxy version that is pinned in Packages.Data.props

---------

Co-authored-by: Scott Beddall (from Dev Box) <[email protected]>
Co-authored-by: Scott Beddall <[email protected]>

Author: azure-sdk

eng/Packages.Data.props

@@ -466,7 +466,7 @@
   </ItemGroup>
 
   <PropertyGroup>
-    <TestProxyVersion>1.0.0-dev.20250805.1</TestProxyVersion>
+    <TestProxyVersion>1.0.0-dev.20250922.2</TestProxyVersion>
     <UnbrandedGeneratorVersion>1.0.0-alpha.20250922.1</UnbrandedGeneratorVersion>
     <AzureGeneratorVersion>1.0.0-alpha.20250903.2</AzureGeneratorVersion>
   </PropertyGroup>

eng/common/testproxy/target_version.txt

@@ -1 +1 @@
-1.0.0-dev.20250805.1
+1.0.0-dev.20250922.2