canonical wds service

[ilrudie]

Please provide a description of this PR:

This is a super early draft for creating "canonical" wds services.

As I worked to optimize ztunnel xds handling and service resolution, it became apparent that the lookup could be optimized all the way to something like, "Is in my namespace ELSE is canonical". When working on "is canonical" it became apparent that this could be a boolean field calculated by istiod instead of a field populated by ztunnel during xds handling.

TODO:

• clean my scribbling from the comments
• better testing
• ztunnel implementation
• some form of "preferred namespace" implementation (ztunnel presently supports this in-proxy. As a result, some way to produce this behavior is likely table stakes for any sort of rationalizing of service resolution in ambient.)

[stevenctl]

last comment is that we probably want Waypoint to be consistent with the ztunnel logic added in istio/ztunnel#1704

We already get the intra-namespace dedupe logic from the sidecar code (timestamps, service > service entry) but we don't get the "prefer namespace local"

that could be added with something like this:

https://gist.github.com/stevenctl/9e7aca7e889ddf0970d7d0a60aa438ec

[stevenctl]

LGTM but can we create a follow up if we want to make waypoint consistent with zt on the "prefer local namespace" case.

[keithmattix]

/retest

[ilrudie]

/retest-required

[ilrudie]

/retest-required