fix: restore legacy suffix compatibility

[zeitlinger]

Fixes #2095

Summary

Restores OM1/protobuf compatibility for dotted gauge names after
feat: move suffix handling to scrape time (#1955).

The bug was that non-OpenMetrics exposition changed visible output for gauge
names that merely ended in suffix-like dotted strings such as .created and
.total.

Examples:

• Gauge("test3.created") regressed from test3 to test3_created
• Gauge("test6.total") regressed from test6 to test6_total

This PR restores the legacy OM1/protobuf behavior while keeping OpenMetrics on
literal-name handling.

This is the extracted prom-side fix from #2093. The Micrometer workflow and
related downstream testing were split into a stacked follow-up PR so this can
merge independently.

What changed

• Fix OM1 text exposition for dotted gauge names ending in .created and
  .total
• Fix protobuf exposition for the same compatibility cases
• Add regression tests that cover the restored OM1/protobuf behavior and the
  preserved OpenMetrics behavior
• Clean up protobuf family-name resolution so legacy gauge handling lives in
  one path instead of pre-rewriting metadata objects

Follow-up stacked PR

• Micrometer workflow/task split: feat: add micrometer compatibility workflow zeitlinger/client_java#1

Related

• Replaces: fix: restore OM1/protobuf micrometer suffix compatibility #2093
• Issue: bug: restore OM1/protobuf suffix compatibility after #1955 #2095

Testing

• mise run build
• mise run lint
• ./mvnw test -pl prometheus-metrics-exposition-textformats,prometheus-metrics-exposition-formats -Dtest=ExpositionFormatsTest,ProtobufExpositionFormatsTest,DuplicateNamesProtobufTest -Dcoverage.skip=true -Dcheckstyle.skip=true