Fix missing inclusion of neo4j_schema in custom prompt generation

[koyonkym]

Description

Fixed the Text2CypherRetriever initialization method so that the instance can hold neo4j_schema when custom_prompt is provided.

I assume some users might want to make a custom prompt based on DEFAULT_TEMPLATE, leaving parameters in it. When initializing the class with neo4j_schema, examples, and custom_prompt like above then searching query_text without prompt_params, examples is embedded in the prompt, but neo4j_schema is not. So I fixed this behavior so that both parameters are embedded in the prompt, which is more consistent.

Type of Change

• New feature
• Bug fix
• Breaking change
• Documentation update
• Project configuration change

Complexity

Complexity: Low

How Has This Been Tested?

• Unit tests
• E2E tests
• Manual tests

Checklist

The following requirements should have been met (depending on the changes in the branch):

• Documentation has been updated
• Unit tests have been updated
• E2E tests have been updated
• Examples have been updated
• New files have copyright header
• CLA (https://neo4j.com/developer/cla/) has been signed
• CHANGELOG.md updated if appropriate

[stellasia]

Hi @koyonkym , Thank you for this PR, I think it makes sense indeed to use the schema when it's provided, similarly to the other parameters.

I think you need to rebase to fix the e2e tests (there was an issue with them that has been fixed after you opened your PR), after that we should be able to merge.