fix BECCS capacities in 2020 to zero

[tabeado]

Purpose of this PR

Currently, all operating CCS projects are set as bounds for 2020 and REMIND decides freely about which capture technologies to use. globally, the split is about 50:50 for BECCS and fossil CCS, leading to 20Mt BECCS in 2020 and 27 Mt in 2025.
However, in 2020 there were 3 BECCS plants in the USA (ethanol+CC, which we don't model), which total a maximum of 1 Mt captured, and one in Japan (bioigccc with 0.18 Mt).
We thus set vm_cap for all BECCS technologies to 0 in 2020.

For policy runs, this does not make a difference. However, in NPis the head-start for BECCS makes a big difference.

Type of change

(Make sure to delete from the Type-of-change list the items not relevant to your PR)

• Minor change (default scenarios show only small differences)

Checklist:

• My code follows the coding etiquette
• I performed a self-review of my own code
• I explained my changes within the PR, particularly in hard-to-understand areas
• I checked that the in-code documentation is up-to-date
• All automated model tests pass (FAIL 0 in the output of make test)

Further information (optional):

See this development issue for effects on NPi

[amerfort]

Thank you so much for doing this!

[amerfort]

Thanks Tabea!