daemon: Fix prefix length tracking on policy failure
daemon: Fix prefix length tracking on policy failure

In policy addition, one of the first functions adds references to the
specified prefixes into the prefix length tracker. However, when the
policy add fails it was not guaranteeing to release these references.
Fix this up by adding a call to d.prefixLengths.Remove() in each of the
error conditions.

Fixes: #4929

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

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