Description

#3745 wired the new onDrop callback of InMemoryTelemetryBuffer for the log buffer so that oversized or unencodable logs record client report outcomes (buffer_overflow / internal_sdk_error).

The metric buffer (created in InMemoryTelemetryProcessorIntegration._createMetricBuffer) does not pass onDrop, so metrics dropped by the buffer (item exceeds maxBufferSizeBytes, or the encoder throws) are silently lost without any discarded-event outcome.

Expected

Metrics dropped by the buffer record a client report outcome with the trace_metric data category:

• buffer_overflow when the encoded item exceeds the buffer limit
• internal_sdk_error when encoding fails

Notes

• The onDrop infrastructure already exists in in_memory_buffer.dart; this is mostly wiring in processor_integration.dart analogous to the log buffer.
• See https://develop.sentry.dev/sdk/telemetry/client-reports/ for discard reasons.

Related: #3751 (same gap for spans). Follow-up to #3745.