[IPAM] fix uninstall

[fra98]

Description

This PR fixes the uninstall with the new IPAM.
In particular, it sets a specific annotation to networks installed with Helm. Since these are required through the whole lifecycle of Liqo, we do not add a finalizer since we do not need to unmap them (as we are uninstalling anyway).

[adamjensenbot]

Hi @fra98. Thanks for your PR!

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[fra98]

/test