Fix exporter tests to have reasonable dates (#38436)

The java time formatter used in the exporter adds a plus sign to the
year, if a year with more than five digits is used. This changes the
creation of those timestamp to only have a date up to 9999.

Closes #38378

Author: spinscale

x-pack/plugin/monitoring/src/test/java/org/elasticsearch/xpack/monitoring/MonitoringTestUtils.java

@@ -23,6 +23,9 @@
 
 public final class MonitoringTestUtils {
 
+    // maximum number of milliseconds before a five digit year comes in, which could change formatting
+    private static  final long MAX_MILLIS_BEFORE_10000 = 253402300799999L;
+
     private MonitoringTestUtils() {
     }
 
@@ -37,7 +40,7 @@ public static MonitoringDoc.Node randomMonitoringNode(final Random random) {
         final String host = fakeTransportAddress.address().getHostString();
         final String transportAddress = fakeTransportAddress.toString();
         final String ip = fakeTransportAddress.getAddress();
-        final long timestamp = RandomNumbers.randomLongBetween(random, 0, Long.MAX_VALUE);
+        final long timestamp = RandomNumbers.randomLongBetween(random, 0, MAX_MILLIS_BEFORE_10000);
 
         return new MonitoringDoc.Node(id, host, transportAddress, ip, name, timestamp);
     }
@@ -87,8 +90,7 @@ public static MonitoringBulkDoc randomMonitoringBulkDoc(final Random random,
                                                             final MonitoredSystem system,
                                                             final String type) throws IOException {
         final String id = random.nextBoolean() ? RandomStrings.randomAsciiLettersOfLength(random, 5) : null;
-        // ending date is the last second of 9999, should be sufficient
-        final long timestamp = RandomNumbers.randomLongBetween(random, 0L, 253402300799000L);
+        final long timestamp = RandomNumbers.randomLongBetween(random, 0L, MAX_MILLIS_BEFORE_10000);
         final long interval = RandomNumbers.randomLongBetween(random, 0L, Long.MAX_VALUE);
         return new MonitoringBulkDoc(system, type, id, timestamp, interval, source, xContentType);
     }