selectorcache: Release identities without sc.Mutex
selectorcache: Release identities without sc.Mutex

Similar to the prior commit, when releasing identities, it is possible
for the identity allocator to attempt to hold SelectorCache.mutex while
handling the release of identities. Therefore, this commit moves the
release of identities outside of the critical section for the
SelectorCache during AddFQDNSelector() (during selector creation), as
well as during the removal of the selector from the SelectorCache.

Found by code inspection.

Signed-off-by: Joe Stringer <16a9a54ddf4259952e3c118c763138e83693d7fd@cilium.io>

michi-covalent/cilium,michi-covalent/cilium,michi-covalent/cilium,cilium/cilium,cilium/cilium,michi-covalent/cilium,michi-covalent/cilium,cilium/cilium,cilium/cilium,cilium/cilium