fix logline mentioning plugin api

[Raffo]

Description

This PR changes a logline that was merged at the time in which we implemented the webhook functionality. This was originally called "plugin" and it looks like a logline mentioning the old name is still in the codebase. This PR renames that to webhook.

Checklist

• [ ] Unit tests updated
• [ ] End user documentation updated

[mloiseleur]

/lgtm /approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: mloiseleur

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• ~~OWNERS~~ [mloiseleur]

Approvers can indicate their approval by writing /approve in a comment Approvers can cancel approval by writing /approve cancel in a comment