ALLEN_INSTALL_DIR in release points to /workspace/build/ALLEN/

It looks like the v1r0 release of Allen is not usable out of the box in Moore with the following symptom

CRITICAL: Could not find Allen sequence file $ALLEN_INSTALL_DIR/constants/Sequence.json; make sure you have built Allen

The reason is that ALLEN_INSTALL_DIR points to the local directory at the time of the release build:

lb-run Moore/v51r1 | grep '^ALLEN_'
ALLEN_INSTALL_DIR=/workspace/build/ALLEN/ALLEN_v1r0/InstallArea/x86_64-centos7-gcc9-opt
ALLEN_PROJECT_ROOT=/cvmfs/lhcb.cern.ch/lib/lhcb/ALLEN/ALLEN_v1r0

The sequence file is otherwise installed as expected at /cvmfs/lhcb.cern.ch/lib/lhcb/ALLEN/ALLEN_v1r0/InstallArea/x86_64-centos7-gcc9-opt/constants/Sequence.json.

It is not clear to me what the proper way of fixing this is. As far as I can tell there is no precedent in generating some data, installing it and then finding it at runtime. (There's only component libraries and python packages.) We could work around by looking at $ALLEN_PROJECT_ROOT/InstallArea/$BINARY_TAG/constants/Sequence.json but I am not sure that's robust enough.

WDYT @clemenci @raaij ?