Downgrade Camel version to 4.18.x

[jbonofre]

ActiveMQ 6.2.9 upgraded to Camel 4.21.x by mistake (see #2351): Camel 4.21.x requires Spring 7.x but ActiveMQ 6.2.9 is still on Spring 6.x. This cause errors when trying to use Camel in ActiveMQ.

On activemq-6.2.x branch, we should stick on Camel 4.14.x.

I will downgrade the Camel version on the branch and I propose either:

1. To propose 6.2.10 with the fix (right Camel version)
2. Or warn users that Camel is not usable out of the box in 6.2.9.