Padding never used - remove?

[AUdaltsova]

Detailed Description

There is a lot of padding handling currently, e g here, that as far as I can see we don't use, as allow_partial_slice defaults to False and is not controllable by user other than recoding it to True by hand directly in the pipeline. We should either remove it or, if we plan on using this, allow for turn on-turn off for the user (probably from the config)

(Personally, I'd rather remove in the spirit of not used - not copied, but there might be some secret usecase I don't know about, so up for debate)

Also, all the tests for this function have allow_partial_slice set to True (see this and other tests in the same file), which should be either changed or more tests added, as we are not actually testing for default behaviour of the function it seems?

[dfulu]

I think this should be discussed at some point in a meeting. This currently isn't being used, but we should have a discussion about what we do when we have partial coverage from a data source. We do face this in the UK when predicting for the Shetlands GSP and we employ something similar but probably bad practice