Backport 15k collection test from master to 3.2

With the completion of TOOLS-1088, a test that restored 15k collections was created to ensure this didn't crash the tools. The work for TOOLS-1088 backport is in progress, but it will not include these tests as the fail on certain variants consistently. This is blocked on backporting of resmoke.py to the 3.2 tools to prevent this test from being run where it would consistently fail.