Fix cell allocation with spread instances

[PhilippMatthes]

Libvirt instances can be spread across multiple cells. In this case, we want to only add the actual allocation of the instance to each cell, and not the total allocation. The implementation assumes that, when instances are spread across multiple cells, they allocate their resources evenly.

[github-actions]

Merging this branch will increase overall coverage

Impacted Packages	Coverage Δ	🤖
github.com/cobaltcore-dev/kvm-node-agent/internal/libvirt	40.00% (+0.57%)	👍

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Coverage by file

Changed files (no unit tests)

Changed File	Coverage Δ	Total	Covered	Missed	🤖
github.com/cobaltcore-dev/kvm-node-agent/internal/libvirt/libvirt.go	71.50% (+0.58%)	200 (+4)	143 (+4)	57	👍

Please note that the "Total", "Covered", and "Missed" counts above refer to code statements instead of lines of code. The value in brackets refers to the test coverage of that file in the old version of the code.

Changed unit test files

• github.com/cobaltcore-dev/kvm-node-agent/internal/libvirt/libvirt_test.go