Creates a new arraylist for collecting vectors and assigning null after

[shatejas]

for OffheapVectorTransfer

Not assigning vector to null is causing bad references for byte and binary cases, the garbage collection is not kicking in causing circuit breaker exceptions when vectors are added individually

Check List

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

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