[Backport release/2.12.x]fix(sendconfig): Do not cleanup `null`s in plugin configuration (#7751)#7780

randmonkey wants to merge 1 commit intorelease/2.12.xKong/kubernetes-ingress-controller:release/2.12.xfrom

backport-7751-to-release/2.12.xKong/kubernetes-ingress-controller:backport-7751-to-release/2.12.xCopy head branch name to clipboard