Fix NoMethodError for RefsController

What does this MR do and why?

• Contributes to #351520 (closed)
• Sentry error: https://sentry.gitlab.net/gitlab/gitlabcom/issues/3146698

Fix a typo and add a test

There is a typo in method name

How to set up and validate locally

http://127.0.0.1:3000/flightjs/Flight/-/refs/%5E/logs_tree

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.