Searching change request does not look into discussions

Right now it's possible to search for change requests based on title / description. However, the search will never look into the various comments created in the change request when searching.

Reproduction steps:

• Create a change request
• Add a new global comment, diff comment, or review comment with a specific word (e.g. "Buzzword")
• In the global search look for this specific word ("Buzzword")

Expected result:

• the change request should appear as this word is used in a discussion on it

Obtained result:

• there's no result, or if the hidden pages are displayed, the result is an hidden page inside the change request space