fix(deps): adapt yaml v3 bump for CI

[cursor]

What this PR does:

Supersedes the failing checks on #7284. Keeps the Renovate dependency bump to go.yaml.in/yaml/v3 and updates Tempo call sites for YAML v3 API compatibility:

• replaces removed UnmarshalStrict / SetStrict usage with KnownFields-based strict decoding
• updates local custom YAML unmarshalers to the *yaml.Node interface where required
• preserves tempo-cli migrate config YAML output formatting under the new encoder

Which issue(s) this PR fixes:
Supersedes #7284 CI failures.

Checklist

• Tests updated
• Documentation added
• Changelog entry added under .chloggen/ (run make chlog-new, or make chlog-new FILENAME=<name> to override the default branch-name file; see .chloggen/README.md)

Validation:

• go test ./pkg/util/listtomap ./modules/overrides/userconfigurable/client ./modules/overrides ./modules/generator/storage ./cmd/tempo ./cmd/tempo-cli ./integration/util
• go test $(go list ./... | rg -v '^github.com/grafana/tempo/integration/(api|limits|metrics-generator|operations|storage)$')

Not run locally:

• make fmt / Docker-backed Make targets and full Docker integration packages: this cloud image does not have a docker executable.

  

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