idpool: Remove erroneous index cache
idpool: Remove erroneous index cache

The index was trying to act as an index to the ids slice. However, the index
was not properly fixed up when an ID was removed from the middle of the slice.
There is no need for the complicated index mechanism, simply use a hashtable
and leverage the random map range behavior to pick a random number.

Fixes: #6632

Signed-off-by: Thomas Graf <5f50a84c1fa3bcff146405017f36aec1a10a9e38@cilium.io>

tklauser/cilium,tgraf/cilium,cilium/cilium,michi-covalent/cilium,michi-covalent/cilium,tgraf/cilium,tgraf/cilium,tgraf/cilium,cilium/cilium,tklauser/cilium,michi-covalent/cilium,tklauser/cilium,michi-covalent/cilium,cilium-team/cilium,tklauser/cilium,cilium/cilium,tklauser/cilium,cilium/cilium,michi-covalent/cilium,tgraf/cilium,tgraf/cilium,cilium/cilium,cilium-team/cilium