pkg/endpoint: check endpoint state before trying to regenerate
pkg/endpoint: check endpoint state before trying to regenerate

* check if endpoint state is able to be changed to waiting-to-regenerate before
trying configuration update
* return error if after a hardcoded timeout, regeneration is unable to occur if
endpoint state not able to be changed to waiting-to-regenerate.

Signed-off by: Ian Vernon <ian@cilium.io>

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