otlptracegrpc otlpconfig adds DialOptions to DialOptions if has DialOptions

[rackerWard]

Description

It is not clear what is the intent of the following code https://github.com/open-telemetry/opentelemetry-go/blob/main/exporters/otlp/otlptrace/otlptracegrpc/internal/otlpconfig/options.go#L144

	if len(cfg.DialOptions) != 0 {
		cfg.DialOptions = append(cfg.DialOptions, cfg.DialOptions...)
	}

Environment

• OS: [e.g. iOS]
• Architecture: [e.g. x86, i386]
• Go Version: [e.g. 1.15]
• opentelemetry-go version: [e.g. v0.14.0, 3c7face]

Steps To Reproduce

1. Use the configuration '...'
2. Run '...'
3. See error

Expected behavior

A clear and concise description of what you expected to happen.

[pellared]

Thank you for reporting. I created #4684