Use bolt icon for Automations sidebar item

What does this MR do and why?

When the duo_automations feature flag is on, the project super sidebar's Automate > Automations item now uses the new bolt icon. With the flag off, the item keeps its Triggers title and trigger-source icon.

Only the sidebar changes. The automations page components still use trigger-source.

Do not merge before !263126 (merged). The bolt icon was first released in @gitlab/svgs 3.168.0, and master still pins 3.167.1. This branch will be rebased once that bump lands.

References

• Dependency: !263126 (merged)
• Feature flag rollout: https://gitlab.com/gitlab-org/gitlab/-/work_items/632894
• Feature: https://gitlab.com/groups/gitlab-org/-/work_items/23940

Closes https://gitlab.com/gitlab-org/gitlab/-/work_items/634920+s

Screenshots or screen recordings

To be added after rebasing onto the @gitlab/svgs 3.168.0 bump.

Before	After

How to set up and validate locally

1. Make sure @gitlab/svgs is 3.168.0 or later and run yarn install.
2. In the Rails console, run Feature.enable(:duo_automations).
3. Open a project with GitLab Duo features enabled, as a user who can manage AI flow triggers.
4. In the left sidebar, select Automate. The Automations item shows the bolt icon.
5. Run Feature.disable(:duo_automations) and reload. The item reads Triggers and shows the trigger-source icon.

MR acceptance checklist

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