feat: Switch from Mosquitto to EMQX as a default MQTT broker

[ppawlowski]

Description

This pull request replaces Mosquitto with EMQX as a default MQTT broker.

The changes introduced in this pull request allows to replace existing Mosquitto broker with the EMQX one without any changes to the helm chart values file. However, I am not aware of an impact from the Node-RED/other MQTT clients' perspective. @hardillb @knolleary, please assess if this should be a minor or major helm chart version bump.

Related Issue(s)

Closes #920

Checklist

• I have read the contribution guidelines
• Suitable unit/system level tests have been added and they pass
• Documentation has been updated
  • Upgrade instructions
  • Configuration details
  • Concepts
• Changes flowforge.yml?
  • Issue/PR raised on FlowFuse/helm to update ConfigMap Template
  • Issue/PR raised on FlowFuse/CloudProject to update values for Staging/Production
• Link to Changelog Entry PR, or note why one is not needed.

Labels

• Includes a DB migration? -> add the area:migration label

[hardillb]

@ppawlowski just checking, will there still be a flowforge-broker service after the upgrade? I'm looking at the diff and can't tell.

Because there will be existing running NR instances that might still be expecting that hostname/service to exist

[knolleary]

At this stage, if we aren't 100% comfortable with the migration paths have been tested and validated, we shouldn't be shipping this tomorrow.

[ppawlowski]

@ppawlowski just checking, will there still be a flowforge-broker service after the upgrade? I'm looking at the diff and can't tell.

Because there will be existing running NR instances that might still be expecting that hostname/service to exist

Wasn't aware of this. Service is now restored.

[hardillb]

Tested this upgrade locally and it all looks to work correctly, would like to merge before Tuesdays extra release.