update:tool-versions fails when gitlab.default_branch is set to a commit SHA

Summary

The rake update:tool-versions task fails when gitlab.default_branch is configured to use a commit SHA instead of a branch name.

The vast majority of sentry errors are caused by this, shown as a GDK::Shellout::ExecuteCommandFailedError.

It is worth noting that this error is not surfaced to users when running gdk update.

Workaround is for users to set gitlab.default_branch to a branch, instead of using commit sha.

Steps to reproduce

1. Set gitlab.default_branch to a commit SHA in your GDK configuration
2. Run gdk rake update:tool-versions
3. Observe the failure

What is the current bug behavior?

The task fails because def git_fetch_version_files in tool_versions_updater.rb uses git checkout origin/{branch}, which doesn't work when the "branch" is actually a commit SHA.

Proposal

The task should handle both branch names and commit SHAs correctly, checking out the appropriate reference without assuming it's always a branch.

Possible fixes

Use git checkout FETCH_HEAD -- '*_VERSION' after git fetch origin #{branch_or_commit}, this should handle both branch names and commit SHAs.