[Canonical] - Keep legacy IDs in the canonical data

[piconti]

Some importers keep the legacy IDs inherited from the OLR/OCR data, for backwards compatibilty and to allow an easier tranfer of the augmentations to the libraries.

However it's not the case for all of them, and it should be added.
The acrion points for this issue would be:

• Identify which importers maintain the legacy IDs and which don't
• Modify the importers which don't to keep the legacy IDs
• Debug and test logic
• Comment code changes accordingly