Setup and teardown integ tests' dependencies effectively

[lwolczynski]

We should consider how we might effectively setup and teardown these integ tests' dependent environments in integ/util.go:dostartIwfServiceWithClient to achieve this in the future.

integ/util.go:dostartIwfServiceWithClient AFAICT sets up the iwf process and connection to the backing provider(cadence/temporal) for each test. We may be able to expand on this to track all started wf's and make sure they are closed on each test execution such that we don't have to explicitly add this behavior to each test in the future.

Originally posted by @bowersj27 in #540 (review)