[$40] Fix candidates list in `GET /taas-teams/:teamId/jobs/:jobId` endpoint

[maxceem]

If we have the same user added as a candidate multiple times, then this endpoint returns incorrect data:

• It returns the same Canidate records multiple times:

  

• But it should return different Candidate records, and only userId and jobId would be the same.

Example request with incorrect data: https://api.topcoder-dev.com/v5/taas-teams/16718/jobs/13c44f0c-9d5f-440d-8e3c-626c766ee122
Note, that if we use another endpoint to get candidate, we get correct data: https://api.topcoder-dev.com/v5/jobCandidates?jobId=13c44f0c-9d5f-440d-8e3c-626c766ee122

• This is caused by the incorrect logic here https://github.com/topcoder-platform/taas-apis/blob/dev/src/services/TeamService.js#L271-L297
• While fixing it, we have to make sure, that we don't request user details several times for the same user https://github.com/topcoder-platform/taas-apis/blob/dev/src/services/TeamService.js#L273

[maxceem]

Challenge https://www.topcoder.com/challenges/250fa49a-e618-44ac-9028-a7c1b6d402a1 has been created for this ticket.

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[maxceem]

@imcaizheng this is open for pickup now. But please, give priority to another issue #151

[maxceem]

Challenge https://www.topcoder.com/challenges/250fa49a-e618-44ac-9028-a7c1b6d402a1 has been assigned to aaron2017.

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[imcaizheng]

PR created #160