fix multi-collection unfccc ingest rows

[diversemix]

• Get multiple-collections working
• add test for 2 collections

Description

Please include:

• a summary of the changes
• links to any related issue/ticket
• any additional relevant motivation and context
• details of any dependency updates that are required for this change

Type of change

Please select the option(s) below that are most relevant:

• Bug fix
• New feature
• Breaking change

How Has This Been Tested?

Please describe the tests that you added to verify your changes.

Reviewer Checklist

• The PR represents a single feature (small driveby fixes are also ok)
• The PR includes tests that are sufficient for the level of risk
• The code is sufficiently commented, particularly in hard-to-understand areas
• Any required documentation updates have been made
• Any TODOs added are captured in future tickets
• No FIXMEs remain