fix test (Azure#49576)

Author: jaschrep-msft

sdk/storage/Azure.Storage.Blobs/tests/ClientSideEncryptionTests.cs

@@ -375,7 +375,10 @@ public async Task OpenWriteAsync(ClientSideEncryptionVersion version, long dataS
                 // compare data
                 Assert.AreEqual(expectedEncryptedData, encryptedData);
 
-                var asBlockBlob = InstrumentClient(disposable.Container.GetBlockBlobClient(blobName));
+                // can't get a block blob client with CSE enabled. Get fresh client without CSE options.
+                BlockBlobClient asBlockBlob = InstrumentClient(BlobsClientBuilder.GetServiceClient_SharedKey()
+                    .GetBlobContainerClient(disposable.Container.Name)
+                    .GetBlockBlobClient(blobName));
                 BlockList list = (await asBlockBlob.GetBlockListAsync()).Value;
                 if (list.CommittedBlocks.Count() > 1)
                 {