OTLP/gRPC message size limit is fixed at 4MB

If the decompressed grpc message exceeds 4MB, the collector sending to apm-server logs the following error.
```
2024-11-25T04:08:26.561Z error internal/queue_sender.go:100 Exporting failed. Dropping data. {"kind": "exporter", "data_type": "traces", "name": "otlp", "error": "not retryable error: Permanent error: rpc error: code = ResourceExhausted desc = grpc: received message after decompression larger than max (6624956 vs. 4194304)", "dropped_items": 11613}
go.opentelemetry.io/collector/exporter/exporterhelper/internal.NewQueueSender.func1
go.opentelemetry.io/collector/exporter@v0.110.0/exporterhelper/internal/queue_sender.go:100
```

The limit comes from the default 4MB grpc server message size limit `MaxRecvMsgSize` in https://pkg.go.dev/google.golang.org/grpc#MaxRecvMsgSize .

## Current user workarounds
- if batchprocessor is used, adjust the config values to influence the payload size
- use otlphttpexporter in place of otlpexporter in the collector sending to apm-server.

## Proposed solution
apm-server should either document or adjust the limit, or make it configurable.