[#69] Fix survey completed field

[roberlander2]

Description

This PR fixes a bug where the list of all survey responses across all users for a given list of surveys is used to determine which surveys the requesting user has completed.

Resolves #69

Review Time Estimate

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Type of changes

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• [x] Bug fix (non-breaking change which fixes an issue).
• [ ] New feature (non-breaking change which adds functionality).
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected).
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Checklist:

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• [x] I have signed the Rokwire Contributor License Agreement (CLA). (Any contributor who is not an employee of the University of Illinois whose official duties include contributing to the Rokwire software, or who is not paid by the Rokwire project, needs to sign the CLA before their contribution can be accepted.)
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• [x] I have performed a self-review of my own code.
• [x] I have commented my code, particularly in hard-to-understand areas.
• [ ] My change requires updating the documentation.
• [ ] I have made necessary changes to the documentation.
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• [x] New and existing unit tests pass locally with my changes.
• [x] Any dependent changes have been merged and published in downstream modules.

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[stefanvit]

@roberlander2 i misunderstood and I thought it should not be based on the current user. Thank you! LGTM!