Fix inconsistency in formatting of comments in switch statements

This was introduced by f7543b2, which only updated the logic for for JDK 17+.

Fixes #1127

PiperOrigin-RevId: 659616575

core/src/main/java/com/google/googlejavaformat/java/JavaInputAstVisitor.java

@@ -1875,10 +1875,10 @@ public Void visitCase(CaseTree node, Void unused) {
     markForPartialFormat();
     builder.forcedBreak();
     if (node.getExpression() == null) {
-      token("default", plusTwo);
+      token("default", ZERO);
       token(":");
     } else {
-      token("case", plusTwo);
+      token("case", ZERO);
       builder.space();
       scan(node.getExpression(), null);
       token(":");

core/src/test/resources/com/google/googlejavaformat/java/testdata/LegacySwitchComment.input

@@ -0,0 +1,17 @@
+class T {
+  int test(String v) {
+    switch (v) {
+      // this is a line comment about "zero"
+      case "zero":
+        return 0;
+      case "one":
+        // this is a line comment about "one"
+        return 1;
+      // this is a line comment about "two"
+      case "two":
+        return 2;
+      default:
+        return -1;
+    }
+  }
+}

core/src/test/resources/com/google/googlejavaformat/java/testdata/LegacySwitchComment.output

@@ -0,0 +1,17 @@
+class T {
+  int test(String v) {
+    switch (v) {
+      // this is a line comment about "zero"
+      case "zero":
+        return 0;
+      case "one":
+        // this is a line comment about "one"
+        return 1;
+      // this is a line comment about "two"
+      case "two":
+        return 2;
+      default:
+        return -1;
+    }
+  }
+}