MULE-7463: Fix logic error in test which was being camuflaged as flackyness

(cherry picked from commit 6dc3f8926382ee35206a49ef9b5188b578e86965)

Conflicts:
	core/src/test/java/org/mule/tck/probe/JUnitProbe.java
MULE-7809: Removing test for receivebuffersize. The value is just a suggestion, so the assertion fails on some environments.

(cherry picked from commit d5f91c75537821874ae415ec9735bd81e3d2ce16)