Cleanup: Use Envoy `contains` for header routing

[davinci26]

Please describe the problem you have
[A clear, concise, description of the problem you are facing. What is the problem that feature X would solve for you?]

In func containsMatch(s string, ignoreCase bool) *envoy_route_v3.HeaderMatcher_StringMatch

contour/internal/envoy/v3/route.go

Line 826 in cca0691

func containsMatch(s string) *envoy_route_v3.HeaderMatcher_StringMatch {

we implement it with safe_regex matching but we can switch to use contains which is the native way of envoy to do this

See https://www.envoyproxy.io/docs/envoy/latest/api-v3/type/matcher/v3/string.proto

[github-actions]

Hey @davinci26! Thanks for opening your first issue. We appreciate your contribution and welcome you to our community! We are glad to have you here and to have your input on Contour. You can also join us on our mailing list and in our channel in the Kubernetes Slack Workspace

[davinci26]

Any objection if I add good first issue and kind\cleanup label?

[sunjayBhatia]

@davinci26 sounds good to me 👍🏽, added those labels

[sunjayBhatia]

from my reading of the API the contains match should mirror what we have, this e2e should confirm: https://github.com/projectcontour/contour/blob/main/test/e2e/httpproxy/header_condition_match_test.go

[skriss]

Worth double-checking behavior for both implementations when the header is not present on the request, xref another issue @davinci26 raised (hopefully the same)