Fix schedule_all_controllers to skip INVALID controllers when enabling

[Chaffelson]

When enabling controller services, NiFi server correctly skips INVALID controllers (those that cannot be enabled due to validation errors). The client was incorrectly waiting for ALL controllers to reach ENABLED state, causing a 30-second timeout when any controller was INVALID.

Now the polling logic only waits for VALID controllers when enabling. When disabling, all controllers are still checked since any controller can be disabled regardless of validation status.

Adds test for mixed VALID/INVALID controller scenario.

[codecov]

Codecov Report

❌ Patch coverage is 83.33333% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 76.50%. Comparing base (0716aee) to head (347d9c6).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
nipyapi/canvas.py	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #400      +/-   ##
==========================================
+ Coverage   76.45%   76.50%   +0.04%     
==========================================
  Files          41       41              
  Lines        4732     4737       +5     
==========================================
+ Hits         3618     3624       +6     
+ Misses       1114     1113       -1     

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