Importer - Ensure mapping ID is set in all places using import templates

[eileenmcnaughton]

This fixes the missing update saved mapping option when using a template

I think I changed the way the metadata was a few times & so it is a bit confusing - but this ensures it is set in the place MapField is expecting it to be

• against 5.61 as the rest of import templates is in there - this is just an issue we hit in live testing

[civibot]

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[eileenmcnaughton]

test this please

[totten]

Note from discussion on MM:

(totten) on first blush, 26108 looks innocent. i'm not sure i understand what it's fixing. was there a discussion somewhere leading to it?
(eileen) yeah - it's a new feature that we are really just putting through it's paces now & we wound up having to add that to get it to work for us - no-one else is likely to have used / tested it more than rudimentary

Since the change is pretty isolated and only relates to this new bit, I'm flagging MOP.