Currently the test tooling, e.g. the commands invoking mlaunch, are using python 2. This was done because some operating systems (ubuntu 12.04 most likely, possibly 14.04 also) did not have a working python 3 implementation - the python 3 that they provided was incapable of installing packages from pypi. While in evergreen there is a newer python available in the toolchain, the docker tooling does not install toolchain python.

We should review whether all presently supported operating systems provide python 3 that is usable, and if so migrate to it.

If a recent enough python 3 can be used everywhere, we should also replace usage of mtools-legacy (which is essentially a fork of mtools from the most recent version that was python 2-compatible with some changes backported) with usage of regular mtools, which could be needed for server 5.2 support.