Update Sample Length when Loading New Sample via Double-Click (#7898)

This PR makes it so that when you double-click on a sample clip and select a new sample, it will automatically update the length of the clip, as long as the clip has auto-resize enabled.

include/SampleClip.h

@@ -54,7 +54,6 @@ public:
 	SampleClip& operator=( const SampleClip& that ) = delete;
 
 	void changeLength( const TimePos & _length ) override;
-	void changeLengthToSampleLength();
 	const QString& sampleFile() const;
 	bool hasSampleFileLoaded(const QString & filename) const;