fix: remove appiumVersion from MobileCapabilityType (appium#1325)

Author: enriquegh

src/main/java/io/appium/java_client/remote/MobileCapabilityType.java

@@ -65,10 +65,6 @@ public interface MobileCapabilityType extends CapabilityType {
  */
  String UDID = "udid";
 
- /**
- * Sauce-specific.
- */
- String APPIUM_VERSION = "appiumVersion";
 
  /**
  * Language to set for iOS (XCUITest driver only) and Android.