Downgrade hard bwc break to a TODO for now

Original commit: elastic/x-pack-elasticsearch@73c2a6ee3e

elasticsearch/x-pack/watcher/src/main/java/org/elasticsearch/xpack/watcher/support/WatcherDateTimeUtils.java

@@ -162,6 +162,7 @@ public class WatcherDateTimeUtils {
      * Parse a {@link TimeValue} with support for fractional values.
      */
     public static TimeValue parseTimeValueSupportingFractional(@Nullable String sValue, String settingName) {
+        // TODO we can potentially remove this in 6.x
         // This code is lifted almost straight from 2.x's TimeValue.java
         Objects.requireNonNull(settingName);
         if (sValue == null) {

elasticsearch/x-pack/watcher/src/test/java/org/elasticsearch/xpack/watcher/support/WatcherDateTimeUtilsTests.java

@@ -126,9 +126,6 @@ public class WatcherDateTimeUtilsTests extends ESTestCase {
     }
 
     public void testParseTimeValueWithFractional() {
-        assertEquals("This function exists so 5.x can be compatible with 2.x indices. It should be removed with 6.x", 5,
-                Version.CURRENT.major);
-
         // This code is lifted strait from 2.x's TimeValueTests.java
         assertEquals(new TimeValue(10, TimeUnit.MILLISECONDS), parseTimeValueSupportingFractional("10 ms", "test"));
         assertEquals(new TimeValue(10, TimeUnit.MILLISECONDS), parseTimeValueSupportingFractional("10ms", "test"));