Revert "Preseve timezone when converting Date to moment"

This reverts commit 877988f4.

frontend/src/metabase/lib/time.js

@@ -11,6 +11,6 @@ export function parseTimestamp(value, unit) {
         // workaround for https://github.com/metabase/metabase/issues/1992
         return moment().year(value).startOf("year");
     } else {
-        return moment(value);
+        return moment.utc(value);
     }
 }