[component] Remove incorrect comment on Factory interface (#11017)

#### Description
Removes an incorrect comment from the `component.Factory interface`.

This comment was added via
#4338 when
the extension/receiver/processor/exporter factory types all still [lived
in](https://github.com/mx-psi/opentelemetry-collector/blob/b4be13e74923ebefb521f69a97288ce8d6f51ea9/component/exporter.go#L61)
`component`. Since the factories have been moved to other modules,
`component.Factory` needs to be implementable.

The specific extension/receiver/processor/exporter factory types are
unimplementable since they are defined in internal packages.

<!-- Issue number if applicable -->
#### Link to tracking issue
Related to
#6506

component/component.go

@@ -165,9 +165,6 @@ func (sl StabilityLevel) LogMessage() string {
 }
 
 // Factory is implemented by all Component factories.
-//
-// This interface cannot be directly implemented. Implementations must
-// use the factory helpers for the appropriate component type.
 type Factory interface {
 	// Type gets the type of the component created by this factory.
 	Type() Type