🔧 Repository: Removed Example App from Maintainer Owned Workspaces

### 📜 Description

We have a few workspaces that still have example app and we would like them removed.

The process to removed them would be as follows:

1. Male sure there is a `/dev/index` setup so that the plugin can be ran
2. Delete the `packages/app` and `packages/backend` folders
3. Validate that everything is still working, there should be NO changes in the `/plugins` folder.
4. Create a PR with the changes.

> [!WARNING]
> Please create 1 PR per workspace, do NOT submit it as one big change. If you work on this make sure you complete 1 before starting the next, complete means it is approved and merged.

The list of workspaces that need this done are:

- cicd-statistics
- jaeger
- jenkins
- linkerd
- sentry
- tech-radar

Here are some good examples of the `dev/index` patter:

- Frontend: https://github.com/backstage/community-plugins/blob/main/workspaces/linguist/plugins/linguist/dev/index.tsx
- Backend: https://github.com/backstage/community-plugins/blob/main/workspaces/linguist/plugins/linguist-backend/dev/index.ts
- New Frontend System: https://github.com/backstage/community-plugins/blob/main/workspaces/entity-validation/plugins/entity-validation/dev/alpha/index.tsx

### 👍 Expected behavior

There should be no example app

### 👎 Current Behavior

There is an example app

### 👟 Reproduction steps

N/A

### 📃 Provide the context for the Bug.

This will help reduce dependencies that need to be updated and better align workspaces with what we expect from other new plugin contributions.

### 👀 Have you spent some time to check if this bug has been raised before?

- [x] I checked and didn't find similar issue

### 🏢 Have you read the Code of Conduct?

- [x] I have read the [Code of Conduct](https://github.com/backstage/community-plugins/blob/main/CODE_OF_CONDUCT.md)

### Are you willing to submit PR?

No, I don't have time to work on this right now

Start in the listed workspaces: cicd-statistics, jaeger, jenkins, linkerd, sentry, and tech-radar. For one workspace at a time, inspect its plugins and the packages/app and packages/backend folders, using the linked dev/index examples as entry-point references. Done means the workspace runs through /dev/index, the example folders are removed, the plugins folder is unchanged, and the workspace has its own approved and merged PR.

Written by the indexing model from the issue text.