overwritePluginsFromImage works not as expected

[bmaehr]

Describe the bug

When setting overwritePluginsFromImage=false I would expect that the plugins from image stay in their version but plugins from installPlugins or additionalPlugins are added. But that fails, because the "/usr/share/jenkins/ref/plugins" is Read-only file system.

In fact I just try to get a setup where a list of base plugins are downloaded while the docker build phase and then some additional plugins could be added through the chart. But I was not able to get this - IMHO not very special - use case to work

Version of Helm and Kubernetes

- Helm: 3.10.2
- Kubernetes: v1.29.6-gke.1254000

Chart version

4.12.1

What happened?

1. Add plugins to custom image by jenkins-plugin-cli
2. Use custom image in chart
3. Add additional plugins to installPlugins
4. Container is not starting up

What you expected to happen?

Have the plugins form the base image and from installPlugins or additionalPlugins

How to reproduce it

No response

Anything else we need to know?

No response