Add `_WILDCARD_TOKEN` special case in `_chop_path`

Add `_WILDCARD_TOKEN` special case in `_chop_path`

### Description
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Add special case to `_chop_path` for initial `_WILDCARD_TOKEN` matching `_DEFAULT_TOKEN` to allow for a top level `undefer_group` load option with other load options. Fixes #9870.

### Checklist
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This pull request is:

- [ ] A documentation / typographical error fix
	- Good to go, no issue or tests are needed
- [x] A short code fix
	- please include the issue number, and create an issue if none exists, which
	  must include a complete example of the issue.  one line code fixes without an
	  issue and demonstration will not be accepted.
	- Please include: `Fixes: #<issue number>` in the commit message
	- please include tests.   one line code fixes without tests will not be accepted.
- [ ] A new feature implementation
	- please include the issue number, and create an issue if none exists, which must
	  include a complete example of how the feature would look.
	- Please include: `Fixes: #<issue number>` in the commit message
	- please include tests.

**Have a nice day!**

Closes: #9931
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/9931
Pull-request-sha: c073f0904f12909ff660beef6576f6476a725592

Change-Id: Ic1158b3b0306e9a1bba86ab0b9f07700a6352398