Fix Constructed Inventory colliding with defaults on controller_inventory_sources

[Klaas-]

What does this PR do?

Follow up to #720 references #601

this changes the behaviour to allow modifications in constructed inventories, for example if you want to set a limit or modify source_vars.

I've updated the test constructed inventory to use both features.

How should this be tested?

Constructed inventory in tests/configs/inventory_sources.yml should work

Is there a relevant Issue open for this?

references #601

Other Relevant info, PRs, etc

#720

[mr-oz-09]

Hello, Will this be merged soon? We are waiting on this fix.

[adrienmrgn]

I think it miss the integration test, because the inventory source definition for the constructed inventory has no organisation defined, so fall back to Default, whereas the related inventory has moved to Satellite org

[djdanielsson]

please update this PR to fix the conflicts and any other requested changes or I will close it soon because it has just been sitting here

[djdanielsson]

closing due to this being open for so long and no movement