Assume that rollover datemath tests run on the same day. (elastic#34527)

in elastic#28741 RolloverIT fails because we are cutting over to the
next day while the test executes. We assume that this doesn't happen
based on the assertions in the test. This adds a assumeTrue to ensure
we are at least 5 min away form a date-flip.

Closes elastic#28741

server/src/test/java/org/elasticsearch/action/admin/indices/rollover/RolloverIT.java

@@ -274,6 +274,7 @@ public void testRolloverOnExistingIndex() throws Exception {
 
     public void testRolloverWithDateMath() {
         ZonedDateTime now = ZonedDateTime.now(ZoneOffset.UTC);
+        assumeTrue("only works on the same day", now.plusMinutes(5).getDayOfYear() == now.getDayOfYear());
         String index = "test-" + DateFormatters.forPattern("YYYY.MM.dd").format(now) + "-1";
         String dateMathExp = "<test-{now/d}-1>";
         assertAcked(prepareCreate(dateMathExp).addAlias(new Alias("test_alias")).get());