Fix br compression size regression in Blazor WASM (#27659)

Reacting to dotnet/runtime#72266, which changed CompressionLevel.Optimal to no longer mean "smallest size", but instead a balance between compression speed and output size. In Blazor WASM publishing, we really want smallest size - it is preferred to spend more time during publish in order for less bytes to be downloaded and cached in the browser.

The fix is to change the default compression level to SmallestSize in the brotli tool used by WASM publish.

src/BlazorWasmSdk/Tool/Program.cs

@@ -22,7 +22,7 @@ public static int Main(string[] args)
 
             var compressionLevelOption = new Option<CompressionLevel>(
                 "-c",
-                getDefaultValue: () => CompressionLevel.Optimal,
+                getDefaultValue: () => CompressionLevel.SmallestSize,
                 description: "System.IO.Compression.CompressionLevel for the Brotli compression algorithm.");
             var sourcesOption = new Option<List<string>>(
                 "-s",