SpringBoot Remove values from JavaVersion enum for Java versions less than 17

With the JDK 17 baseline, having constants for Java 16 and below is pointless as our JavaVersion class can only be loaded on a Java 17 or later VM.

Comment From: daixi98

Hi @wilkinsona, any suggestion on the OnJavaCondition class?

@Test
void boundsTests() {
    testBounds(Range.EQUAL_OR_NEWER, JavaVersion.NINE, JavaVersion.EIGHT, true);
    testBounds(Range.EQUAL_OR_NEWER, JavaVersion.EIGHT, JavaVersion.EIGHT, true);
    testBounds(Range.EQUAL_OR_NEWER, JavaVersion.EIGHT, JavaVersion.NINE, false);
    testBounds(Range.OLDER_THAN, JavaVersion.NINE, JavaVersion.EIGHT, false);
    testBounds(Range.OLDER_THAN, JavaVersion.EIGHT, JavaVersion.EIGHT, false);
    testBounds(Range.OLDER_THAN, JavaVersion.EIGHT, JavaVersion.NINE, true);
}

Comment From: wilkinsona

I think it'll be easiest to wait until we've added EIGHTEEN (https://github.com/spring-projects/spring-boot/issues/29524).