[SM-190] Add integration tests to Secrets

[Thomas-Avery]

Type of change

- [ ] Bug fix
- [ ] New feature development
- [] Tech debt (refactoring, code cleanup, dependency upgrades, etc)
- [ ] Build/deploy pipeline (DevOps)
- [X] Other

Objective

This PR is for adding the rest of integration tests for secrets.

Code changes

• test/Api.IntegrationTest/Controllers/SecretsControllerTests.cs

Adding integration tests for Create, Update, and Reads

Before you submit

• Please check for formatting errors (dotnet format --verify-no-changes) (required)
• If making database changes - make sure you also update Entity Framework queries and/or migrations
• Please add unit tests where it makes sense to do so (encouraged but not required)
• If this change requires a documentation update - notify the documentation team
• If this change has particular deployment requirements - notify the DevOps team