…tic#77109)

Preview datafeed currently fails when the time field is of type
`date_nanos`. The failure contains the error message:

```
date [...] is after 2262-04-11T23:47:16.854775807 and cannot be
stored in nanosecond resolution
```

This commit fixes this failure. The cause of the issue was that
preview generates a search with a range query on the time field
whose upper bound is `Long.MAX_VALUE` in order to include all
available data in the preview. However, that value is parsed
with `DateUtils.toLong` when the time field is `date_nanos` and
it hits the limitation that values can't be larger than
`DateUtils.MAX_NANOSECOND_INSTANT`. The fix checks whether the
time field is `date_nanos` and uses `DateUtils.MAX_NANOSECOND_INSTANT`
as the upper bound instead of `Long.MAX_VALUE`.