CMSSW_7_6_7 image with condition db files for the tutorial

Prepare an image with CMSSW_7_6_7 and the following two db's

$ ls -lh /cvmfs/cms-opendata-conddb.cern.ch/76*
-rwxr-xr-x. 1 cvmfs cvmfs 1.1G Oct  4  2021 /cvmfs/cms-opendata-conddb.cern.ch/76X_dataRun2_16Dec2015_v0.db
-rwxr-xr-x. 1 cvmfs cvmfs 644M Oct  4  2021 /cvmfs/cms-opendata-conddb.cern.ch/76X_mcRun2_asymptotic_RunIIFall15DR76_v1.db

To be decided if this should go to the latest of the current images:

cmsopendata/cmssw_7_6_7-slc6_amd64_gcc493
gitlab-registry.cern.ch/cms-cloud/cmssw-docker-opendata/cmssw_7_6_7-slc6_amd64_gcc493

or be a separate image with another name.