[Dynamic Instrumentation] Change the way we are using the gzip stream in SymDB (#6562)

## Summary of changes

When we upload symbols, we want to use the underline stream after we are
disposing the gzip stream

---------

Co-authored-by: Andrew Lock <andrew.lock@datadoghq.com>

Author: dudikeleti

tracer/src/Datadog.Trace/Debugger/Upload/SymbolUploadApi.cs

@@ -84,24 +84,25 @@ public override async Task<bool> SendBatchAsync(ArraySegment<byte> symbols)
 
             MultipartFormItem symbolsItem;
 
-            if (_enableCompression)
+            if (!this._enableCompression)
+            {
+                symbolsItem = new MultipartFormItem("file", MimeTypes.Json, "file.json", symbols);
+            }
+            else
             {
                 using var memoryStream = new MemoryStream();
 #if NETFRAMEWORK
-                using var gzipStream = new Vendors.ICSharpCode.SharpZipLib.GZip.GZipOutputStream(memoryStream);
-                await gzipStream.WriteAsync(symbols.Array, 0, symbols.Array.Length).ConfigureAwait(false);
-                await gzipStream.FlushAsync().ConfigureAwait(false);
+                using (var gzipStream = new Vendors.ICSharpCode.SharpZipLib.GZip.GZipOutputStream(memoryStream))
 #else
-                using var gzipStream = new GZipStream(memoryStream, CompressionMode.Compress);
-                await gzipStream.WriteAsync(symbols.Array, 0, symbols.Array.Length).ConfigureAwait(false);
-                await gzipStream.FlushAsync().ConfigureAwait(false);
+                using (var gzipStream = new GZipStream(memoryStream, CompressionMode.Compress))
 #endif
+                {
+                    await gzipStream.WriteAsync(symbols.Array, 0, symbols.Array.Length).ConfigureAwait(false);
+                    await gzipStream.FlushAsync().ConfigureAwait(false);
+                }
+
                 symbolsItem = new MultipartFormItem("file", MimeTypes.Gzip, "file.gz", new ArraySegment<byte>(memoryStream.ToArray()));
             }
-            else
-            {
-                symbolsItem = new MultipartFormItem("file", MimeTypes.Json, "file.json", symbols);
-            }
 
             var items = new[] { symbolsItem, new MultipartFormItem("event", MimeTypes.Json, "event.json", _eventMetadata) };