Error in `azdev setup` - `No such file or directory: '_NONE_/scripts/ci/cmdcov.yml'`

@bobjac and I are extension authors for an "external" extension that resides in its own repository, e.g. https://github.com/Azure/partnercenter-cli-extension

Since June 16, our CI is failing with the following error when calling `azdev setup`, regardless of args.
```
[Errno 2] No such file or directory: '_NONE_/scripts/ci/cmdcov.yml'
Traceback (most recent call last):
File "/Users/kehilli/Workspace/github.com/partner-center-cli/env/lib/python3.11/site-packages/knack/cli.py", line 233, in invoke
cmd_result = self.invocation.execute(args)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/kehilli/Workspace/github.com/partner-center-cli/env/lib/python3.11/site-packages/knack/invocation.py", line 134, in execute
self.commands_loader.load_arguments(command)
File "/Users/kehilli/Workspace/github.com/partner-center-cli/env/lib/python3.11/site-packages/azdev/__main__.py", line 30, in load_arguments
from azdev.params import load_arguments
File "/Users/kehilli/Workspace/github.com/partner-center-cli/env/lib/python3.11/site-packages/azdev/params.py", line 13, in
from azdev.operations.linter import linter_severity_choices
File "/Users/kehilli/Workspace/github.com/partner-center-cli/env/lib/python3.11/site-packages/azdev/operations/linter/__init__.py", line 21, in
from .linter import LinterManager, LinterScope, RuleError, LinterSeverity
File "/Users/kehilli/Workspace/github.com/partner-center-cli/env/lib/python3.11/site-packages/azdev/operations/linter/linter.py", line 17, in
from azdev.operations.regex import (
File "/Users/kehilli/Workspace/github.com/partner-center-cli/env/lib/python3.11/site-packages/azdev/operations/regex.py", line 19, in
with open(os.path.join(get_cli_repo_path(), 'scripts', 'ci', 'cmdcov.yml'), 'r') as file:
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
FileNotFoundError: [Errno 2] No such file or directory: '_NONE_/scripts/ci/cmdcov.yml'
```

This happens locally as well after `pip install azdev`, which installs the latest version of azdev package.

We've tested back to version 0.1.48 and that version works.

Start by reproducing `azdev setup` after installing the latest package against an external extension, then read `azdev.operations.regex` at the `get_cli_repo_path()` lookup shown in the traceback. Compare the behavior with version 0.1.48 and verify that setup no longer tries to open the missing `scripts/ci/cmdcov.yml` path for external extensions.

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