The TSGroupMember table is updated after every inserted interaction. It
asserts that the sender of the interaction is in the group membership.
Before, our tests would construct groups with mock membership and then
construct outgoing messages with the local address as the sender. This
would fail this new requirement.
The fix is to make sure that the local address is in the test group
membership if we'd like to "send" any messages.
21f0fcb2ff
