Enable zstd compression on gmessage topic by default (#919)

The data shows average of 1.5x reduction in message size on 2k network
for partial gmessage sizes.

Based on the testing, so far it's harmless and beneficial to have
compression on gmessage topic enabled.

Author: masih

manifest/manifest.go

@@ -55,7 +55,7 @@ var (
 	}
 
 	DefaultPubSubConfig = PubSubConfig{
-		CompressionEnabled:             false,
+		CompressionEnabled:             true,
 		ChainCompressionEnabled:        true,
 		GMessageSubscriptionBufferSize: 128,
 		ValidatedMessageBufferSize:     128,

manifest/manifest_test.go

@@ -124,8 +124,8 @@ func TestManifest_CID(t *testing.T) {
 	t.Parallel()
 
 	const (
-		wantLocalDevnetCid = "baguqfiheaiqh6vtsf7fionpvi2gp3xwz5vbtbkaabcb7gidub2skahnzjclq5wy"
-		wantAfterUpdateCid = "baguqfiheaiqoplbaxrgczvmuiihl3zypbrbqmorvs2yeynm7bcnhkxeq6q2sz2y"
+		wantLocalDevnetCid = "baguqfiheaiqoktbekgcqvdpzlfnxvcocafjj5n6enxsokutvkkfqi6vrowr4gay"
+		wantAfterUpdateCid = "baguqfiheaiqiqtpn555ipnmjfp6ehzfymrtb5p5gyu2gmq74nohxlxwvhy3dx3y"
 	)
 	subject := manifest.LocalDevnetManifest()
 	// Use a fixed network name for deterministic CID calculation.