Title is duplicated in chunk if present in the index as contextual content

Problem/Motivation

In order to have more metadata on the chunk of content that is being converted to embeddings and later stored in vector database, the title of the entity is added to each chunk as a headline 1. This happens of course only when title (entity label field) is present in the index fields and is not "Ignored". But this also leads to the duplication of the title, as it is later added to the end of the chunk as contextual content with label of the field and its value.

Steps to reproduce (required for bugs, but not feature requests)

Install ai_search module

• Install any VDB provider and configure it
• Create a Search API server with AI Search backend and use the VDB provider installed on previous step.
• Create an index for "Content" entity type.
• Add "Rendered HTML output" field as "Main content" and "Title" field as "Contextual content".
• Index at least 1 item
• Check the chunk, it will contain the content title as h1 ('#') in the beginning of the chunk and also `Title: here is the title of the content` in the end.

Proposed resolution

Do not include the title in the end of the chunk, as the title is already added in the beginning. This will save some tokens and will allow to use them more efficiently.
Alternatively, do not add title as h1 but leave the title in the chunk metadata.

Remaining tasks

Decide on the approach, create MR