This looks correct to:
"testdate" : "2019-07-09T04:29:55.000+05:30"
is indeed a date coming from:
"date" : "7/9/2019 4:29:55 PM"
parsed with "M/d/yyyy HH:m:s a".
What else do you expect?
timestamp is just an information (an ingest meta data) which will not be part of your document at the end. It's the date when you ran the ingest pipeline actually.