Fix secure credential loading for nested team-config profiles

[ATorrise]

What It Does
When testing #408 i found that the way i structured my config was returning 401s
ie:

mainframe ->
  -> properties
       -> host
  -> profiles
       -> zosmf ->
            -> properties
                 -> port
            -> secure
                 -> user
                 -> password

found that __load_secure_properties looked for zosmf as a direct key of the mainframe profile but zosmf actually lives one level deeper, under the profiles key.

the fix to config_file.py handles however many levels a config nests

test_custom_file_and_custom_profile_loading_with_nested_profile user/password values came from a plaintext override in nested.zowe.config.user.json, not from the vault. So apparently no test ever exercised __load_secure_properties for a profile nested more than one level deep with secure fields on the child! Added a new test (test_nested_profile_with_secure_properties_on_child) that pulls creds from the mocked vault
How to Test
change your config to match this level of nesting when testing. verify that you get 401s on main and you can run system tests on this branch :)
Review Checklist
I certify that I have:

• updated the changelog
• manually tested my changes
• added/updated automated unit/integration tests
• created/ran system tests (provide build number if applicable)
• followed the contribution guidelines

Additional Comments

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.40%. Comparing base (91f8021) to head (a411a6a).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #411      +/-   ##
==========================================
+ Coverage   83.06%   83.40%   +0.34%     
==========================================
  Files          49       49              
  Lines        2982     2983       +1     
==========================================
+ Hits         2477     2488      +11     
+ Misses        505      495      -10     

Flag	Coverage Δ
unittests	83.40% <100.00%> (+0.34%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[zFernand0]

LGTM! 😋

Very good catch! 🙏

Here is a quick before and after of this fix:

Before

{'rejectUnauthorized': False, 'host': 'lpar.1', 'port': 1234}
HTTP Request has failed with status code 401. 

After

{'rejectUnauthorized': False, 'host': 'lpar.1', 'port': 1234, 'user': 'dummy', 'password': 'dummy'}
HTTP Request has failed with status code 401. 

I got the 401 because dummy:dummy is not valid on my system

---

With proper creds:

{'rejectUnauthorized': False, 'host': 'lpar.1', 'port': 1234, 'user': 'REALUSER', 'password': 'PASSWORD'}
//* //FERNAN00 JOB (IZUACCT),FERNANDO,CLASS=B,MSGCLASS=X,TYPRUN=HOLD
...

[traeok]

I noticed that even with these changes, the failure is never raised from check_missing_props, which is likely why @zFernand0 was seeing a 401 rather than an explicit error. I'd consider it out of scope for this PR, but worth a follow-up issue.

Aside from that, I left a suggestion around the modified code in an attempt to de-duplicate logic.

[traeok]

I know the loop is pre-existing, but this walk looks identical to find_profile. Could we just use that instead and remove this whole loop?

For example:

profile = self.find_profile(".".join(segments), self.profiles)
if isinstance(profile, dict):
    profile.setdefault("properties", {})[property_name] = value