testutil.pm now contains a few miscellaneous functions that are used in
several places but have no better place to live. subvariables moves to
servers.pm since most variables that it substitutes relate to servers,
so this is the most appropriate place. Rename a few functions for better
naming consistency.
Ref: #10818Closes#10995
This is code that is directly responsible for running a single test.
This will eventually run in a separate process as part of the parallel
testing project.
Ref: #10818
Dan Fandrich