Artemis: Refactor QueryRequest cache key generation for performance

[mike-turintech]

This commit refactors the cache key generation logic for QueryRequest objects to improve performance and simplicity.

Previously, the key was generated by serializing relevant fields into a JSON string using ObjectMapper and then hashing the JSON. This approach introduced overhead and unnecessary complexity.

The new implementation directly constructs a delimited string (field:value;...) from the request fields using a StringBuilder and hashes this raw string.

Benefits include:

• Improved performance by avoiding JSON serialization.
• Simplified key generation logic.
• Removal of dependency on ObjectMapper within the method.
• Elimination of JsonProcessingException handling.

Related Jackson imports and the objectMapper field have been removed. The fallback mechanism in case of NoSuchAlgorithmException now returns the raw generated string.