When creating a branch the Web IDE and single file editor do not expire branch/tag cache

Summary

When a new branch is created via the Web IDE or the single file editor the branch / tag name cache is not expired.

This poses a security problem because it allows a pipeline to be ran on an ambiguous ref. There is an ambiguity check in the pipeline creation chain, but the branch/tag name cache still doesn't contain the name of the newly created branch/tag which causes the check to pass when in reality it should fail. This allows users to create a branch with the same name as a tag and trigger a pipeline for the tag, possibly leaking protected variables.