prod-202104-01: Changes to workflow generator

* Split TPC clusterization into 2 stages
  so that we can fit into 16GB for ~100PbPb.
* Introduce additional cluster merging step
  to prepare one file for TPC reco
* Add ROOT macro helper for the merge step
  (to be generalized later)
* Adjust some memory/cpu resource estimates
  (based on ~100PbPb dataframes)
* Don't use --rate 1 for TOF reco workflow.
  Now terminates much faster.