MVCCIncrementalIterator currently allows returning inline values via MVCCIncrementalIterInlinePolicyEmit. However, this is not safe to combine with time-bound iterators, which will become enabled by default in #82453 -- these will omit inline values since they do not fall within the time bounds. It is not clear that inline values even make sense for this iterator, since a) they're not MVCC; and b) they don't have timestamps, so we should remove support for them and error if encountered.

The only caller that enables inline values is rangefeeds. It's not clear that they make sense there either. See #69357.

Jira issue: CRDB-16491