Add snowplow events for clicking search suggestions

What does this MR do?

This MR adds the required data-track events as described in https://docs.gitlab.com/ee/development/telemetry/snowplow.html#tracking-in-haml-or-vue-templates in order to allow us to measure usage of the search autocomplete feature.

These search autocomplete links are rendered by the deprecated_jquery_dropdown so we needed to extend this class to pass the relevant attributes down to where the link is created.

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Closes #241055