Clean up temporary files from tests

[tkelman]

and make replcompletions test more robust to only finding a single completion

In combination with other tests setting random seeds, I actually fairly often see collisions in my /tmp folder of directories that haven't been deleted from past test runs. Some of those are from tests that fail and it's a little harder to keep track of those, but at least these I found as being created even when tests succeed, then not being cleaned up.

There are still 3 left in the parallel test here

julia/test/parallel_exec.jl

Lines 360 to 362 in fe23b88

	if !is_windows()
	# these give unlink: operation not permitted (EPERM) on Windows
	rm(fn); rm(fn2); rm(fn3)

that I'm not quite sure what to do about, I've tried forcing finalization of the SharedArrays there but so far haven't gotten anything to work. fixed, yay