Add ability to override e-tag for specific samples that have broken metadata

Add ability to override e-tag for specific samples that have broken metadata. This will allow autoconfiguration at analysis stage to work as expected and use the actual generator used (and not the picked up during EVNT to EVNT step).

@fladias, @rlysak, @maklein, this should be included in the next PHYS production.

/cc @ancuetog @sargyrop @ewelina @averbyts @yharris @mmuskinj