Make pyaerocom lustre agnostic

[dulte]

To make pyaerocom usable for external users, as well as for internal users, all assumptions that lustre is/should be connected should be removed

[github-actions]

This issue is stale because it has been open for 365 days with no activity. This issue will be closed in 14 days if no action is taken.

[avaldebe]

this issue is still relevant...

[jgriesfeller]

Starting to work on this again since the NorESM people want to run pyaerocom on NIRD. Starting to investigate on how to trick pyaerocom into using a different path but still thinking that is lustre.
Apparently just changing paths in variables.ini is not enough due hard coded paths in other code places