[Caideyipi]

Summary

• Include table-model measurements (field count x device count) in per-region series gauges.
• Add regression coverage for both total and non-view counts.

Validation

• mvn spotless:apply -pl iotdb-core/datanode
• git diff --check
• The targeted Maven test reaches DataNode compilation but is blocked by a stale local relational grammar artifact: AstBuilder references generated copyToStatement() methods absent from the installed parser jar.

[alpass163]

Suggest that adding a new metric rather than change the count logic of the existed