Remove writing redundant binary doc value copy of jVector based vectors.

[akash-shankaran]

Description

Presently jvector writes 2 copies of vector files:

1. Store the vectors inline (which end up in .data-jvector files)
2. vectorField with DocValuesType.BINARY (which end up in .dvd files)

The .dvd copy is never read by jVector, as all its readers rely on being served from the inline vector graph.
This leads to higher storage and added overhead on index build, and merge times.

Given modifying doc values of existing indices could lead to issues, this change is safe for newer indices created in v3.9.0.0 onwards.

Advantages:

1. This should result in a significant storage improvement, and bring the jvector-plugin on parity with other opensearch based engines.
2. Side benefits: Reduce merge times, and index build times.

Experimental Data:
Measured on sift-100k (128d) PQ, 1 shard force-merged to 1 segment:
index size goes from 125.18 MB to 76.50 MB (-38.9%), with data-jvector file being byte-identical and no impact on recall@k and recall@1. The removed ~50MB bytes is one fp32 copy (100000 x 128 x 4).

Related Issues

Resolves #716

Check List

• New functionality includes testing.
• New functionality has been documented.
• API changes companion pull request created.
• Commits are signed per the DCO using --signoff.
• Public documentation issue/PR created.

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