Python: MagenticBuilder logs spurious custom-manager warning with defaults

[moonbox3]

Description

MagenticBuilder always emits a misleading warning when a custom manager is provided, even with no extra manager args.

In _set_manager, _log_warning_if_constructor_args_provided checks max_stall_count, which defaults to 3 (non-None), so the warning always fires:

"Custom manager provided; all other manager arguments will be ignored."

Code Sample

from agent_framework_orchestrations import MagenticBuilder

# using any valid participants + custom manager
builder = MagenticBuilder(participants=[...], manager=my_manager)
# Actual: warning logged even when no constructor overrides were passed
# Expected: no warning unless override args were explicitly supplied

Error Messages / Stack Traces

No exception. Incorrect warning behavior.

Package Versions

agent-framework-orchestrations: source checkout at commit 02ba27493

Python Version

Python 3.13.5

Additional Context

This can create false-positive warning noise in normal custom-manager usage.