Related issue: Resolves https://github.com/fleetdm/fleet/issues/26225
## Testing
- [x] QA'd all new/changed functionality manually
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## Summary by CodeRabbit
- **New Features**
- Added an Android AMAPI mock service for load testing.
- Added configurable image version selection and optional Google API
request forwarding.
- Added routing for mock and API requests through the internal load
balancer.
- Added secure storage and optional access to Google service-account
credentials.
- Exposed the mock service endpoint for downstream load-test
configuration.
- Configured the load-testing environment to use the new internal proxy
endpoint.
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Konstantin Sykulev
6613872eda