Automatic merge from submit-queue (batch tested with PRs 48279, 48566, 48319, 48794, 47952)

Add prometheus plugin on fluentd image.

**What this PR does / why we need it**:
This PR adds the prometheus plugin on Fluentd.

**Special notes for your reviewer**:
The plugin used was: https://github.com/kazegusuri/fluent-plugin-prometheus, on the latest stable version.
All configs used are default.

**Release note**:

```release-note
Fluentd-es addon now exposes a /metrics endpoint for monitoring on port 24231. 
```