Add test in the CI that heavily uses gap junctions

[iomaganaris]

Currently the CI didn't manage to catch an issue like https://github.com/BlueBrain/CoreNeuron/issues/667

Describe the solution you'd like We should try and reproduce this issue with another small test (maybe https://github.com/nrnhines/tqperf) and add it to the CI

Additional context A small test based on olfactory-bulb-3d model should also be included in the CI