fix: Drop all capabilities for init container

[ppawlowski]

Description

This PR adds a drop of all capabilities for init container. The main reasons of not making this parameter configurable are:

• init container does single, simple task which does not require capabilities to be modified
• I am pretty sure that init container is a short term solution of how we are passing configuration parameters to the forge app and will not stay with us for a long time

I have tested such configuration locally and init container does its job as expected.

Related Issue(s)

https://github.com/FlowFuse/CloudProject/issues/320
https://github.com/FlowFuse/CloudProject/issues/319

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

Labels

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