Fix: Correctly report filter notifications on Java agent teardown

Fix: Correctly report filter notifications on Java agent teardown

If a Java agent gets disposed, it should not just clear() all its
tracked event rules: it should first send corresponding filter change
notifications indicating that these rules are not tracked anymore.

This fixes a problem where if event rules were still enabled on agent
tear down, the filter notifier's own tracked events would become out
of sync.

Signed-off-by: Alexandre Montplaisir <alexmonthy@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>