kvstore/allocator: protect concurrent access of slave keys
kvstore/allocator: protect concurrent access of slave keys

If a key is released from localKeys and marked as last used, it
will be released from the KVStore. Unfortunately, this has a concurrent
issue if at the same time this localKey allocated which means
cilium-agent will update its value into the KVStore. If this update
happens before the delete call, the key is forever deleted from the
KVStore.

Signed-off-by: André Martins <bc9800b9d52a24cce72a73dd528afed53f10e5fc@cilium.io>

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