[MartinForReal]

What type of PR is this?

/kind bug

What this PR does / why we need it:

This replaces the stale #1210. Current master already uses OpenTelemetry: #1297 merged the OpenCensus -> OpenTelemetry metrics migration, and the remaining OpenCensus references are historical comments. The original #1210 branch was therefore reduced to the one behavior on top of current master that is still missing.

ParsePrometheusMetrics (used by the e2e helper that scrapes NPD /metrics) currently returns an error for any family type it does not recognize. A Prometheus exposition may contain a sample without a # TYPE line; the text parser reports that family as UNTYPED. One such family therefore fails parsing of the whole scrape, even when all NPD counters/gauges parsed successfully.

This PR makes ParsePrometheusMetrics skip family types it does not support instead of aborting, while keeping the existing handling:

• COUNTER and GAUGE values;
• SUMMARY sample sums;
• HISTOGRAM sample sums.

Malformed exposition (bad labels, duplicate TYPE lines, trailing garbage) still returns a parse error.

Which issue(s) this PR fixes:

Refs #1008. The migration itself landed in #1297; this PR remains as a parsing robustness fix discovered during that migration. Refs #1210 for history.

Special notes for your reviewer:

Changes

• pkg/util/metrics/helpers.go: unsupported family types are skipped, and the function documentation states which family types are returned.
• pkg/util/metrics/helpers_test.go: table tests cover explicit UNTYPED and implicit (no TYPE) families, and pin SUMMARY/HISTOGRAM sample sums.

Behavior

No change to the metrics NPD emits, its metric names, labels, or OpenTelemetry configuration. The change only affects parsing of Prometheus text by this helper.

Validation

• Linux unit suite (all packages except the live GCP test/e2e suites): pass.
• Focused Windows packages (pkg/util/metrics/..., pkg/exporters/..., pkg/problemmetrics/...): pass, and go vet passes.
• go.mod, go.sum, vendor/: unchanged relative to upstream master.
• Final whole-branch review: no blocking findings.

Does this PR introduce a user-facing change?

NONE

[kubernetes-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[MartinForReal]

Closing as requested. The remaining parsing fix is not being pursued in this PR.