Fix build, remove eodatasets1 dependency

[jeremyh]

There's no reason to use eodatasets1 now -- move remaining code to eodatasets3.

• The CI was broken due to black/flake8 mismatches. I've fixed those and also upgraded the CI settings to match the eugl repo.
• the ard_pbs script wasn't detected by black/etc, but it is now, so the diff is a little larger. Can disable this if needed. I've disabled pyupgrade too, as the unnecessary changes are larger.
• I initially started porting the s2-nci-processing, but realised it's too outdated to still be used by anyone -- it hard-codes collection paths that have long since been removed. So I've removed it instead. Tell me if we'd prefer to keep it.

[uchchwhash]

Looks great!