[TEST] only reset clients on nightly tests
resetting the clients on each test (in after test) makes the tests running, especially in network mode, much slower, since transport client needs to be created each time when randmized to be used. Also, on OSX, the excessive connections causes bind exceptions eventually which makes running the network tests much harder on it.
closes #7329
[STORE] Ignore segments.gen on metadata snapshots

The segments.gen file is optional and might even change while we
read it. It's safer to just ignore that file in the snapshot instead.
[STORE] Remove unnecessary deduplication