JVMCBC-1689 (followup) JwtAuthenticator should include SaslListMechanismsHandler

Motivation
----------
Even though we don't strictly need to list the authentication mechanisms,
downstream code that handles auth failure expects to see channel
attributes that were set by `SaslListMechanismsHandler`.

Change-Id: Id1366c864250a5173e9b9bfb3fc33b8ccc2dccf6
Reviewed-on: https://review.couchbase.org/c/couchbase-jvm-clients/+/235874
Tested-by: Build Bot <[email protected]>
Reviewed-by: Graham Pople <[email protected]>

Author: dnault

core-io/src/main/java/com/couchbase/client/core/env/JwtAuthenticator.java

@@ -21,6 +21,7 @@
 import com.couchbase.client.core.deps.io.netty.channel.ChannelPipeline;
 import com.couchbase.client.core.endpoint.EndpointContext;
 import com.couchbase.client.core.io.netty.kv.SaslAuthenticationHandler;
+import com.couchbase.client.core.io.netty.kv.SaslListMechanismsHandler;
 import com.couchbase.client.core.io.netty.kv.sasl.OauthBearerSaslClient;
 import com.couchbase.client.core.json.Mapper;
 import org.jspecify.annotations.NullMarked;
@@ -119,6 +120,7 @@ private JwtAuthenticator(String encodedJwt) {
 
   @Override
   public void authKeyValueConnection(EndpointContext ctx, ChannelPipeline pipeline) {
+    pipeline.addLast(new SaslListMechanismsHandler(ctx));
     pipeline.addLast(new SaslAuthenticationHandler(
       ctx,
       null, // username not required