Automatic merge from submit-queue (batch tested with PRs 67691, 68147). If you want to cherry-pick this change to another branch, please follow the instructions here: https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md.
Bump versions of components with latest security patches.
**What this PR does / why we need it**:
Upgrade versions of monitoring components used on GCP, to include latest security patches.
**Release note**:
```release-note
[fluentd-gcp-scaler addon] Bump fluentd-gcp-scaler to 0.4 to pick up security fixes.
[prometheus-to-sd addon] Bump prometheus-to-sd to 0.3.1 to pick up security fixes, bug fixes and new features.
[event-exporter addon] Bump event-exporter to 0.2.3 to pick up security fixes.
```
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