Remove workaround in GraalVM native Paketo Builder Test

[scottfrederick]

When paketo-buildpacks/native-image#321 has been addressed, we should remove the environment variable setting that works around that problem.

spring-boot/spring-boot-system-tests/spring-boot-image-tests/src/systemTest/resources/org/springframework/boot/image/paketo/PaketoBuilderTests-nativeApp.gradle

Lines 38 to 39 in 0f8062f

	//see https://github.com/paketo-buildpacks/native-image/issues/321
	'BP_NATIVE_IMAGE_BUILD_ARGUMENTS': '-H:-AddAllFileSystemProviders']