Support Prometheus `translation_strategy` configuration

[zeitlinger]

Summary

Implement the translation_strategy configuration option for the Prometheus exporter.

This controls how OTel metric/label names are translated to Prometheus format and whether type/unit suffixes are appended. The converter becomes the single authority for suffix decisions — the OM2 format writer renders names as-is (no smart-append).

Strategies

Strategy	Escaping	expositionBaseName	Labels	__ collapse
UnderscoreEscapingWithSuffixes (default)	prometheusName()	base + unit + type suffix (_total, _info)	prometheusName()	yes
UnderscoreEscapingWithoutSuffixes	prometheusName()	base only	prometheusName()	yes
NoUTF8EscapingWithSuffixes	passthrough	base + unit + type suffix	passthrough	no
NoTranslation	passthrough	raw OTel name (via originalName)	passthrough	no

Key design decision: the converter uses the 4-arg MetricMetadata(name, expositionBaseName, help, unit) constructor to explicitly control what the OM2 writer outputs. sanitizeMetricName() is no longer called (it's a no-op in prom_client_java 1.6+).

Changes required

1. Otel2PrometheusConverter — branch convertMetadata() and convertLabelName() on strategy. Type-aware suffix logic (append _total for counters, _info for info metrics) moves into the converter.
2. PrometheusMetricReaderBuilder — add setTranslationStrategy(TranslationStrategy)
3. PrometheusHttpServerBuilder — delegate to reader builder
4. PrometheusComponentProvider (DC) — wire translation_strategy from config model (enum already exists in generated schema)
5. No env var / system property — DC only, per spec

Dependencies

The NoUTF8EscapingWithSuffixes and NoTranslation strategies depend on prometheus/client_java scrape-time-suffix-handling branch which adds originalName, expositionBaseName, and scrape-time suffix handling. The implementation PR will be a draft until the next prom_client_java release includes these changes.

Previous work

• #7588 — earlier attempt with a utf8 flag, closed in favor of translation_strategy
• #8080 — updated prom client to 1.5.0 with backward-compatible escaping