aggregating several obs networks using aeroval fails when the networks don't provide the same unit natively

[jgriesfeller]

Describe the bug
In CAMS2-82 we put together several obs network to one so that they can be evaluated together. Evaluating e.g. ozone where SINCA provides ozone in ug/m^3 doesn't include SINCA in All obs although it's in the config
All obs (missing e.g SINCA):

But the actual analysis is done despite SINCA using the wrong unit (ug/m^3)

• Pyaerocom version: 0.26.0
• Configuration file (if applicable):
  Look at the experiment at https://aeroval.met.no/pages/evaluation/?project=cams2-82&experiment=IFS

To Reproduce
Steps to reproduce the behavior:
rerun aeroval

Expected behavior
the first image should also contain the SINCA data

Additional context
concerns the variables vmro3 and vmrno2

[lewisblake]

Short fix it to preprocess data to be in correct units