TUN-8904: Rename Connect Response Flow Rate Limited metadata

## Summary

This commit renames the public variable that identifies the metadata key and value for the ConnectResponse structure when the flow was rate limited.

 Closes TUN-8904

connection/quic_connection.go

@@ -186,7 +186,7 @@ func (q *quicConnection) handleDataStream(ctx context.Context, stream *rpcquic.R
 		var metadata []pogs.Metadata
 		// Check the type of error that was throw and add metadata that will help identify it on OTD.
 		if errors.Is(err, cfdflow.ErrTooManyActiveFlows) {
-			metadata = append(metadata, pogs.ErrorFlowConnectRateLimitedKey)
+			metadata = append(metadata, pogs.ErrorFlowConnectRateLimitedMetadata)
 		}
 
 		if writeRespErr := stream.WriteConnectResponseData(err, metadata...); writeRespErr != nil {

connection/quic_connection_test.go

@@ -639,7 +639,7 @@ func TestTCPProxy_FlowRateLimited(t *testing.T) {
 
 		// Got Rate Limited
 		assert.NotEmpty(t, response.Error)
-		assert.Contains(t, response.Metadata, pogs.ErrorFlowConnectRateLimitedKey)
+		assert.Contains(t, response.Metadata, pogs.ErrorFlowConnectRateLimitedMetadata)
 	}()
 
 	tunnelConn, _ := testTunnelConnection(t, netip.MustParseAddrPort(udpListener.LocalAddr().String()), uint8(0))

tunnelrpc/pogs/quic_metadata_protocol.go

@@ -19,8 +19,8 @@ const (
 )
 
 var (
-	// ErrorFlowConnectRateLimitedKey is the Metadata entry that allows to know if a request was rate limited on connect.
-	ErrorFlowConnectRateLimitedKey = Metadata{Key: "FlowConnectRateLimited", Val: "true"}
+	// ErrorFlowConnectRateLimitedMetadata is the Metadata entry that allows to know if a request was rate limited on connect.
+	ErrorFlowConnectRateLimitedMetadata = Metadata{Key: "FlowConnectRateLimited", Val: "true"}
 )
 
 func (c ConnectionType) String() string {