Feat: Implement proper sparse checkout of repos

[ByteOtter]

What this PR does / why we need it:

Implement a proper sparse checkout for the aggregator to improve performance.

Which issue(s) this PR fixes:
Fixes #-

Definition of Done:

• The code is sufficiently documented
• Shared the changes with the Team so everyone is aware
• The code is appropriately tested
• Checked if the code needs to be backportet to release branches of maintained versions (perform the actual backport after the merge to main)

Special notes for your reviewer:

Release note:

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