clean up integration test urls
clean up integration test urls

the endpoints for aodh, ceilometer and gnocchi end with trailing
slash. because of that, our tests are calling <endpoint>//<path>.
this works but is technically incorrect. this patch cleans it up.

Change-Id: I187ea35b6158ac86bc2c4f19597c37e0b75cf2e4

openstack/aodh,openstack/aodh