[MOB-772] fix: use the right v3 host for the create store service.

[jdandrade]

What does this PR do?

Fix the checkUserCredentials base host. Inline variable used only once.

Where should the reviewer start?

• [ ] UploaderApplication.java

How should this be manually tested?

Flow on how to test this or QA Tickets related to this use-case: MOB-772

What are the relevant tickets?

Tickets related to this pull-request: MOB-772

Code Review Checklist

• [ ] Documentation on public interfaces
• [ ] Remove comments & unused code & forgotten testing Logs
• [ ] Codestyle
• [ ] Functional tests pass