[tests] Remove debug prints from corelib/date_time7 test

R=whesse@google.com

CoreLibraryReviewExempt: Test changes only
Change-Id: I1013a0a60cb60ef769e041668bac342b0d44283e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/357604
Reviewed-by: William Hesse <whesse@google.com>
Commit-Queue: Slava Egorov <vegorov@google.com>

tests/corelib/date_time7_test.dart

@@ -21,8 +21,6 @@ testLocal() {
     //
     // Hardcode some common timezones, in both their abbreviated and expanded
     // forms to account for differences between host platforms.
-    print(name);
-    print(offset);
     switch (name) {
       case "CET" || "Central European Time" || "Central European Standard Time":
         Expect.equals(1, offset.inHours);