Refactor OOO Request Schema: Replace requestedBy with userId and Remove userId Field

[RishiChaubey31]

Description

• Schema for requests has been modified and the request body for create OOO needs to be modified to match new schema and requirements. Affected fields include requestedBy, userId.

Current Behaviour

• Username is being stored in requestedBy field while userId has its own separate field

Expected Behavior

• userId should be stored in requestedBy field, removing the need for redundant userId.