Backport of catalog: improve the bound workload identity encoding on services into release/1.18.x

[dhiaayachi]

Backport

This PR is auto-generated from hashicorp#20458 to be assessed for backporting due to the inclusion of the label backport/1.18.

The below text is copied from the body of the original PR.

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Description

The endpoints controller currently encodes the list of unique workload identities referenced by all workload matched by a Service into a special data-bearing status condition on that Service. This allows a downstream controller to avoid an expensive watch on the ServiceEndpoints type just to get this data.

The current encoding does not lend itself well to machine parsing, which is what the field is meant for, so this PR simplifies the encoding from:

"blah blah: " + strings.Join(ids, ",") + "."

to

strings.Join(ids, ",")

It also provides an exported utility function to easily extract this data.

PR Checklist

• updated test coverage
• [ ] external facing docs updated
• appropriate backport labels added
• not a security concern

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Overview of commits

• c0021f6 - 0425833 - 895c075 - 2fe9dd8