Inconsistent retry and timeout behavior across exporters

[XSAM]

Description

otlptracegrpc states that the timeout takes precedence over retry setting, once this time limit has been reached the export is abandoned and the batch of spans is dropped.

opentelemetry-go/exporters/otlp/otlptrace/otlptracegrpc/options.go

Lines 185 to 191 in a85ae98

	// WithTimeout sets the max amount of time a client will attempt to export a
	// batch of spans. This takes precedence over any retry settings defined with
	// WithRetry, once this time limit has been reached the export is abandoned
	// and the batch of spans is dropped.
	//
	// If unset, the default timeout will be set to 10 seconds.
	func WithTimeout(duration time.Duration) Option {

But otlptracehttp uses a different approach where the retry is over the WithTimeout.

opentelemetry-go/exporters/otlp/otlptrace/otlptracehttp/client.go

Line 79 in a85ae98

Timeout: cfg.Traces.Timeout,

opentelemetry-go/exporters/otlp/otlptrace/otlptracehttp/client.go

Line 156 in a85ae98

resp, err := d.client.Do(request.Request)

The resp, err := d.client.Do(request.Request) runs inside the d.requestFunc, which means the timeout of the client won't abandon the retry.

Expected behavior

The retry mechanism should be identical across exporters.

Related: #6588
Related spec topic: it is unclear to me how the timeout of the exporter works with retry: open-telemetry/opentelemetry-specification#4138