Not retrying in case of
isSuccessful() being false.
This change also adds an informational logging message whenever a bulk
If `isSuccessful()` returns false for a bulk indexing result, retrying the whole bulk will lead to infinite loops in case of index mapping errors or other permanent errors. This change also adds an informational logging message whenever a bulk was indexed successfully on the n-th (n > 1) attempt, indicating that indexing has recovered from a formerly erroneous condition. Fixes #3938.