CAMEL-7662 MQTTProducerTest fails once enables it

The assertion expects MQTT publish/disconnect call to be submitted as a async task, i.e. enqueued in a dispatch queue
CAMEL-8052 Added RemovePropertiesDefinition
CAMEL-8052 Improve comments and javadoc related to RemoveProperties
Camel-8052 fixed checkstyle
Camel-8021 Fixed Maven surefire warning during build
CAMEL-7662 Fixed the CS error of camel-mqtt
Camel-8052 Fixed the CS error
Fixed other CS errors in camel-core
CAMEL-8052 Added some unit tests for Spring DSL
Fixed the CS error of camel-metrics