Raise if path isn't a string

What does this MR do and why?

Related to https://gitlab.com/gitlab-org/gitlab/-/issues/371994

Kicking off a quick MR to see if specs fail. I will clean it up with specs depending on how much stuff breaks (if at all!)

Screenshots or screen recordings

N/A

How to set up and validate locally

From the rails console

[1] pry(main)> attack = [ ".." , "..", "..", "..", "..", "..", "..", "..", "..", "..", "etc", "passwd"]
=> ["..", "..", "..", "..", "..", "..", "..", "..", "..", "..", "etc", "passwd"]
[2] pry(main)> Gitlab::Utils.check_path_traversal! attack
Gitlab::Utils::PathTraversalAttackError: Invalid path
from /home/dcouture/gdk/canonical/gitlab/lib/gitlab/utils.rb:20:in `check_path_traversal!'

Previously this did not raise

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

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

lib/gitlab/import_export/decompressed_archive_size_validator.rb

@@ -87,7 +87,6 @@ def validate
       def validate_archive_path
         Gitlab::Utils.check_path_traversal!(@archive_path)
 
-        raise(ServiceError, 'Archive path is not a string') unless @archive_path.is_a?(String)
         raise(ServiceError, 'Archive path is a symlink') if File.lstat(@archive_path).symlink?
         raise(ServiceError, 'Archive path is not a file') unless File.file?(@archive_path)
       end