Fix Java17PreviewFeaturesTests (locale-specific floating-point output)

The test worked on my local workstation with German locale, but not on
GitHub with English locale.

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>

tests/features198/java17/SwitchPatternAspect.aj

@@ -1,4 +1,5 @@
 import java.util.List;
+import java.util.Locale;
 
 aspect SwitchPatternAspect {
   Object around(Object o) : execution(* doSomethingWithObject(*)) && args(o) {
@@ -6,7 +7,7 @@ aspect SwitchPatternAspect {
       case null      -> "null";
       case Integer i -> String.format("int %d", i);
       case Long l    -> String.format("long %d", l);
-      case Double d  -> String.format("double %f", d);
+      case Double d  -> String.format(Locale.ENGLISH, "double %f", d);
       case String s  -> String.format("String %s", s);
       default        -> o.toString();
     });

tests/features198/java17/SwitchPatternOK.java

@@ -1,4 +1,5 @@
 import java.util.List;
+import java.util.Locale;
 
 /**
  * Inspired by examples in https://openjdk.java.net/jeps/406
@@ -26,7 +27,7 @@ public class SwitchPatternOK {
       case null      -> "null";
       case Integer i -> String.format("int %d", i);
       case Long l    -> String.format("long %d", l);
-      case Double d  -> String.format("double %f", d);
+      case Double d  -> String.format(Locale.ENGLISH, "double %f", d);
       case String s  -> String.format("String %s", s);
       default        -> o.toString();
     };

tests/src/test/resources/org/aspectj/systemtest/ajc198/ajc198.xml

@@ -42,7 +42,7 @@
 				<line text="null" />
 				<line text="int 123" />
 				<line text="long 999" />
-				<line text="double 12,340000" />
+				<line text="double 12.340000" />
 				<line text="String foo" />
 				<line text="[123, foo, 999, 12.34]" />
 				<line text="Non-circle" />
@@ -63,7 +63,7 @@
 				<line text="null" />
 				<line text="int 123" />
 				<line text="long 999" />
-				<line text="double 12,340000" />
+				<line text="double 12.340000" />
 				<line text="String foo" />
 				<line text="[123, foo, 999, 12.34]" />
 				<line text="Non-circle" />