CAF stage cannot be run with c14 builds

[fjnicolas]

Running the CAF stage with c14 qualifiers will result in

Can't find file "sbn_cnnid.fcl"

from sbndcode v09_82_02.

We are currently running the CNN hit classiffication module as part of the CAF stage (see #386). This module depends on TensorFlow, for which LArSoft currently only provides e26 builds.

Note: by now we are only providing e26 builds for the SBN/SBND managed repositories, so it's not actually an issue right now.
I'm just opening it for future reference if people attempt to run CAF stage once c14 builds are back.

[bear-is-asleep]

Won't fix since c14 build is not used anyways. Will fix should the necessity arise.

The underlying issue is on the larsoft side building tensorflow with c14, which is needed for the CNN at the CAF stage.