(WIP) Generalize event queue handling in tests
(WIP) Generalize event queue handling in tests

Store the event queue list in the base test class, so operation on the
queues can be delegated to separate method instead of operating on each
queue explicitly.

Change-Id: I4c23143b4d49fa409fe378d1348bb6397b748cb9

gooddata/zuul,gooddata/zuul,gooddata/zuul,gooddata/zuul,gooddata/zuul