Allow partial parsing when default target and profile names are used

[ash2shukla]

Resolves #7612

Problem

If default target and profile names are passed explicitly then the vars hash doesn't get computed correctly as when its not passed explicitly we currently treat profile_name and target_name as empty strings instead of actual resolved names.

Solution

Use resolved profile and target names from config

Checklist

• I have read the contributing guide and understand what's expected of me.
• I have run this code in development, and it appears to resolve the stated issue.
• This PR includes tests, or tests are not required or relevant for this PR.
• This PR has no interface changes (e.g., macros, CLI, logs, JSON artifacts, config files, adapter interface, etc.) or this PR has already received feedback and approval from Product or DX.
• This PR includes type annotations for new and modified functions.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.38%. Comparing base (9cf32c8) to head (cb57eba).
⚠️ Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #12498      +/-   ##
==========================================
- Coverage   91.39%   91.38%   -0.01%     
==========================================
  Files         203      203              
  Lines       25445    25445              
==========================================
- Hits        23256    23254       -2     
- Misses       2189     2191       +2     

Flag	Coverage Δ
integration	88.25% <ø> (-0.02%)	⬇️
unit	65.10% <ø> (ø)

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Components	Coverage Δ
Unit Tests	65.10% <ø> (ø)
Integration Tests	88.25% <ø> (-0.02%)	⬇️

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