Simplify the implementation of vector search filter logic

[Thejas-bhat]

• we don't ideally need two different functions in the interface which can be consolidated as part of the go-faiss's Selector interface, which is actually a parameter to these functions
• needs to be backported to v16.x as well [BP] Simplify implementation of the vector search filter  #396

[abhinavdangeti]

v17.0.9

[CascadingRadium]

Hey @Thejas-bhat, I do not understand the need or the urgency of this PR.
I am seeing some issues here and I am wondering why this PR was merged in with this haste without a proper review from the team, given that the PR was marked as ready for review a few hours back.

1. When we have a search request coming in on a segment with no exclude bitmap (which happens when there are no deleted vectors in the segment) - the exclude bitmap is nil and hence selector too will be nil. In this case, if the params is not nil and selector is nil (for float32 indices), we just call the go-faiss SearchWithSelector API which will error out. This is orthogonal to the earlier behavior where we handled this case well, where we created a valid SearchParams.

2. When using for BIVF indices, in the case where selector is not nil and params is nil, we call SearchWithSelector where simply ignore the selector and call b.Search(xb, k)

3. For BIVF incides again: if selector is nil (no exclusions) and params is not nil, we simply error out.

cc @abhinavdangeti

[abhinavdangeti]

Good spot @CascadingRadium 👍🏼 , let's get these addressed soon.