cleanup discovery logs

[luke-lombardi]

Summary by cubic

Tightened cache discovery warnings to count only unresolved hosts and candidates, reducing noisy and misleading logs. Resolved groups are skipped before counting and verification.

• Bug Fixes
  • Count unresolvedHosts, unresolvedCandidates, and unresolvedEndpointCandidates only for groups without an endpoint in pkg/cache/discovery.go.
  • Early-continue when a group already has an endpoint; exclude from warning totals.
  • Updated warning text to say "unresolved" and report accurate host/candidate counts with the last error.

^{Written for commit 938c0a3. Summary will update on new commits.}