Configuration fixes
- use LCG 101 in
lhcb-run2-prerelease(to match the platforms built) - override the
ccacheversion inlhcb-2017-patchesandlhcb-2018-patchesto work with nightlies-jenkins-scripts!136 (merged)
lhcb-run2-prerelease (to match the platforms built)ccache version in lhcb-2017-patches and lhcb-2018-patches to work with nightlies-jenkins-scripts!136 (merged)