This commit updates the WebSocket message broker configuration to stop
setting a thread name prefix for externally defined Executors.
This used to apply to:
* clientInboundChannel with a thread name prefix of
"clientInboundChannel-".
* clientOutboundChannel with a thread name prefix of
"clientOutboundChannel-".
* brokerChannel with a thread name prefix of "brokerChannel-".
Closes gh-32132
0f707706f1