Write tests for User RPC

[tmthecoder]

Write Tests for User RPC

Context

The User RPC endpoint exposes a CRUD RPC endpoint that allows other services to work with users via RPC. These methods currently have no associated tests and must have some added in.

Requirements & Criteria

• Tests are written within db-service/tests/app.e2e-spec.ts
• Tests cover cases of invalid input (with appropriate exception/error checking)
• Tests cover cases of correct input
• Tests cover all of gRPC methods (create, get, update, delete, link project)

NOTE: The full test-suite for any package can be run in the root directory of the project by running yarn test:e2e:[service-name]