[chore] [pdata] don't generate a cycle import in the internal package (…

…open-telemetry#8552)

To avoid warnings thrown by `make genpdata`:
```
go run pdata/internal/cmd/pdatagen/main.go
/Library/Developer/CommandLineTools/usr/bin/make fmt
package go.opentelemetry.io/collector/internal/fanoutconsumer
	imports go.opentelemetry.io/collector/component
	imports go.opentelemetry.io/collector/pdata/pcommon
	imports go.opentelemetry.io/collector/pdata/internal
	imports go.opentelemetry.io/collector/pdata/internal: import cycle not allowed
package go.opentelemetry.io/collector/internal/fanoutconsumer
	imports go.opentelemetry.io/collector/component
	imports go.opentelemetry.io/collector/pdata/pcommon
	imports go.opentelemetry.io/collector/pdata/internal
	imports go.opentelemetry.io/collector/pdata/internal: import cycle not allowed
```

The invalid imports are removed by `go fmt` after that anyway, but it's
still annoying.