Get Devices incorrectly returns devices that have failed to connect

v1.0.0 has just been installed on b21. Upon spinning up BlueAPI the saxs and waxs detectors have failed to connect because the IOCS are not on. This is reflected in the startup logs and is expected.

However Get Devices still returns the saxs and waxs detectors.

## Steps To Reproduce
Steps to reproduce the behavior:
1. Go to https://b21-blueapi.diamond.ac.uk/docs#/Device/get_devices_devices_get
2. Click on "Try it Out" Then "Execute"
3. Scroll down through the return json and waxs and saxs are shown towards the bottom
4. See that this is in error

## Acceptance Criteria
- Have blueapi startup, fail to connect to the missing devices, then show the same devices that connect in the logs as are returned in Get Devices