Remove type from nested documents; where types used to store nested path information

[dreamer-89]

Remove _type field used to store nested paths

[dreamer-89]

Based on code scan, I think _type references are internal and not exposed to customers. Thus, this change is not a blocking change for v2.0.0. We can target other blocking changes first before picking up this one.

@nknize @reta : What are your thoughts around this ?

[reta]

@dreamer-89 sounds good, to me, thanks!

[dreamer-89]

https://github.com/dreamer-89/OpenSearch/commits/nested-doc-type

After adding NestedPathFieldMapper to replace _type in nested document's parent/child references.

[dreamer-89]

Confirmed with @nknize ; that this is not a blocking change for 2.0 relase.

[dreamer-89]

This is implemented in #3004.

[dreamer-89]

Closing this issue, as relevant PR is merged into main.