Backport of ci: split frontend ember jobs into release/1.15.x#16976

hc-github-team-consul-core merged 2 commits intorelease/1.15.xhashicorp/consul:release/1.15.xfrom

backport/loshz/frontend-test-splitting/tightly-humorous-shrewhashicorp/consul:backport/loshz/frontend-test-splitting/tightly-humorous-shrewCopy head branch name to clipboard