Verify raw GZIP data in Azurite payload tests

Disable transparent download decompression when inspecting stored Blob bytes, and verify the GZIP encoding property alongside the compressed header.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: Bernd Verst

tests/durabletask/test_large_payload_e2e.py

@@ -307,7 +307,9 @@ def echo(ctx: task.OrchestrationContext, inp: str):
         assert len(blobs) > 0, "Expected at least one blob in the container"
         # All blobs should contain compressed data (GZip header: 1f 8b)
         for blob in blobs:
-            data = container_client.download_blob(blob.name).readall()
+            stream = container_client.download_blob(blob.name, decompress=False)
+            assert stream.properties.content_settings.content_encoding == "gzip"
+            data = stream.readall()
             assert data[:2] == b"\x1f\x8b", f"Blob {blob.name} is not GZip-compressed"