Remove unwanted printing of stack trace from the Launcher

Previously, the Launcher would call ex.printStackTrace for any
exception that was thrown when launching the application. This was
unnecessary as the stack trace should already have been logged by
the application when it failed to start.

This commit removes the call to ex.printStackTrace, thereby allowing
an exception to be logged only once or not at all after successful
failure analysis.

Closes gh-5358

spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/Launcher.java

@@ -58,7 +58,6 @@ public abstract class Launcher {
 			launch(args, getMainClass(), classLoader);
 		}
 		catch (Exception ex) {
-			ex.printStackTrace();
 			System.exit(1);
 		}
 	}