[TASK] Fix intermittent failures in SessionTest
At time the garbageCollectionOnlyRemovesTheDefinedMaximumNumberOfSessions
in SessionTest fails with "Failed asserting that 1 matches expected 5."
Since the test is about making sure a maximum is not exceeded, this
changes the assertion from "equal" to "less than or equal".
Releases: master, 2.2, 2.1