BUILDER_TSMP2_PDAF: Remove bin and bld directory of previous build

As of now, every build of TSMP2-PDAF should be a build completely from scratch in an empty directory. Therefore, I add a step for removing binary and build directory of the previous build.

Here is the failed build that I attribute to existing bin/bld from the first successful build: https://esm-buildbot.fz-juelich.de/#/builders/47/builds/2