fix: fix incorrect configuration name reference for cumulocity port

[reubenmiller]

Fix the incorrect reference to the custom Cumulocity client proxy port.

An invalid name was being used which resulted in the default port, 8001, always being used regardless of the configuration file or related environment variables being set.

Resolves #179

[github-actions]

Robot Results

✅ Passed	❌ Failed	⏭️ Skipped	Total	Pass %	⏱️ Duration
38	0	0	38	100	8m50.030356s

Passed Tests

Name	⏱️ Duration	Suite
Get Container Logs	5.954 s	Container-Logs
Get Container Logs with only last N lines	0.717 s	Container-Logs
Get Container Logs By Operation	7.816 s	Container-Logs
Remove Container	9.072 s	Container-Remove
Remove Container Non Existent Container Should Not Through An Error	0.133 s	Container-Remove
Restart Container	0.652 s	Container-Restart
Restart Unknown Container Fails	0.127 s	Container-Restart
Update to tedge-container-plugin-ng	24.304 s	Installation
Check for Update	7.875 s	Operations-Clone
Clone Existing Container	27.856 s	Operations-Clone
Clone Existing Container by Timeout Whilst Waiting For Exit	18.352 s	Operations-Clone
Clone Existing Container but Waiting For Exit	19.788 s	Operations-Clone
Ignore Containers With Given Label	21.400 s	Operations-Clone
Install/uninstall container-image	20.909 s	Operations-Container-Image
Install/uninstall not existent container image	8.895 s	Operations-Container-Image
Install/uninstall container package from private repository - credentials file	13.939 s	Operations-Private-Registries
Install/uninstall container package from private repository - credentials script	14.008 s	Operations-Private-Registries
Install/uninstall container package from private repository - credentials script with cache	21.108 s	Operations-Private-Registries
Install/uninstall container package from private repository - engine credentials	17.657 s	Operations-Private-Registries
Install/uninstall container package from private repository - docker from docker	44.586 s	Operations-Private-Registries
Get Configuration	5.210 s	Operations
Install/uninstall container-group package	17.552 s	Operations
Install/uninstall container-group package with non-existent image	11.258 s	Operations
Install invalid container-group	3.037 s	Operations
Install container-group with multiple files - app1	14.726 s	Operations
Install container-group with multiple files - app2	7.968 s	Operations
Install/uninstall container package	20.130 s	Operations
Install/uninstall container package from file	12.424 s	Operations
Manual container creation/deletion	18.287 s	Operations
Manual container creation/deletion with error on run	7.673 s	Operations
Manual container created and then killed	10.477 s	Operations
Remove Orphaned Cloud Services	19.601 s	Operations
Install container group that uses host volume mount	7.712 s	Operations
Self Update Is Present Using Self Type	0.199 s	Self
Self Update Is Present Using Container Type	0.207 s	Self
Self Update Is Not Present	0.203 s	Self
Service status	17.663 s	Telemetry-Main
Sends measurements	70.556 s	Telemetry-Main