Add vector similarity functions integration tests

[QuerthDP]

This patch introduce the validator integration tests for the vector_similarity() function added in ScyllaDB.

Refs: scylladb/scylladb#25993

[QuerthDP]

The validator tests should pass after scylladb/scylladb#25993 is merged.

You can run them locally with:

run-validator-with-scylla-unshare [path_to_scylla] [path_to_vector_store] [path_to_validator] vector_similarity

[QuerthDP]

Changelog:

• added tests for compound primary keys

It turned out the feature does not work properly if the SELECT does not contain whole primary key.
Turning the PR to draft until it's solved.

Furthermore I believe the tests can be refactored as they're very similar.

[Copilot]

Pull Request Overview

This PR adds comprehensive integration tests for the vector_similarity() function in ScyllaDB. The tests validate that the function correctly returns similarity scores when used with ANN queries across different table schema configurations.

• Adds integration tests for the vector_similarity() function across three different scenarios
• Updates the create_index function to support additional options parameter for vector index configuration
• Ensures existing tests continue to work by passing None for the new options parameter

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

File	Description
crates/validator/src/tests/vector_similarity.rs	New test file containing three test cases for the vector_similarity function
crates/validator/src/tests/mod.rs	Registers the new vector_similarity test module
crates/validator/src/common.rs	Updates create_index function to accept optional configuration parameters
crates/validator/src/tests/*.rs	Updates existing test calls to pass None for the new options parameter

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[QuerthDP]

Changelog:

• extract similarity function result checking
• extract embeddings into a constant

[QuerthDP]

Changelog:

• removed the unnecessary comment
• renamed check_similarity_function_results to assert_similarity_function_results

[QuerthDP]

Changelog:

• renamed vector_similarity_function_returns_expected_results to vector_similarity_function_with_single_column_partition_key

[QuerthDP]

Changelog:

• rebased on master
• adjusted tests with new syntax of vector similarity functions
• using options in lower case to check if db: fix option parsing #248 works properly