Backport of Add upgrade warnings into release/1.16.x#19062

hc-github-team-consul-core merged 2 commits intorelease/1.16.xhashicorp/consul:release/1.16.xfrom

backport/kisunji/vault-ca-upgrade/luckily-winning-emuhashicorp/consul:backport/kisunji/vault-ca-upgrade/luckily-winning-emuCopy head branch name to clipboard