Add create shortcut to RSocketStrategies

Now that RSocketStrategies has default settings it makes sense to have
a create() shortcut vs builder().build().

This commit also updates tests to take advantage of improvements in this
and the previous two commits.

See gh-23314

spring-messaging/src/main/java/org/springframework/messaging/rsocket/RSocketStrategies.java

@@ -114,14 +114,6 @@ public interface RSocketStrategies {
 	 */
 	ReactiveAdapterRegistry reactiveAdapterRegistry();
 
-
-	/**
-	 * Return a builder to build a new {@code RSocketStrategies} instance.
-	 */
-	static Builder builder() {
-		return new DefaultRSocketStrategies.DefaultRSocketStrategiesBuilder();
-	}
-
 	/**
 	 * Return a builder to create a new {@link RSocketStrategies} instance
 	 * replicated from the current instance.
@@ -131,6 +123,24 @@ public interface RSocketStrategies {
 	}
 
 
+	/**
+	 * Create an {@code RSocketStrategies} instance with default settings.
+	 * Equivalent to {@code RSocketStrategies.builder().build()}.
+	 */
+	static RSocketStrategies create() {
+		return new DefaultRSocketStrategies.DefaultRSocketStrategiesBuilder().build();
+	}
+
+	/**
+	 * Return a builder to build a new {@code RSocketStrategies} instance.
+	 * The builder applies default settings, see individual builder methods for
+	 * details.
+	 */
+	static Builder builder() {
+		return new DefaultRSocketStrategies.DefaultRSocketStrategiesBuilder();
+	}
+
+
 	/**
 	 * The builder options for creating {@code RSocketStrategies}.
 	 */