[Documentation] Merging "Query Result Formats" with "Hydration Modes"

[ThomasLandauer]

Page: https://www.doctrine-project.org/projects/doctrine-orm/en/2.19/reference/dql-doctrine-query-language.html#query-result-formats

As announced in https://github.com/doctrine/orm/pull/11372#issue-2190613801, I merged the (mostly) identical sections.

• I changed the consts from Query to AbstractQuery

• I deleted this - mainly cause I didn't find a nice place for it:

  In parentheses are the constants of the Query class which you can use with the general-purpose method Query::execute(array $params = [], $hydrationMode = Query::HYDRATE_OBJECT).

  Should I bring it back?

[greg0ire]

Please squash your commits.

[ThomasLandauer]

Done :-)

[greg0ire]

Thanks @ThomasLandauer !