Use majority concern for all change stream test collections

[eramongodb]

Followup to #1367.

Attempt to resolve more flaky task failures:

change_streams.cpp:388: FAILED: std::distance(stream.begin(), stream.end()) == 1 for: 0 == 1

change_streams.cpp:594: FAILED: one != x.end() for: {?} != {?}

Assuming these are due to the tests not consistently using majority write concern for their operations, as is the case for the prose test that was the focus of the previous PR:

Change streams only notify on data changes that have persisted to a majority of data-bearing members in the replica set.

This PR adds a make_test_coll helper function which drops, creates, and sets concern levels for the collection to be watched and operated on.