Python: Fix GroupChat orchestrator message cleanup issue

[alliscode]

Apply clean_conversation_for_handoff to GroupChatOrchestrator and AgentBasedGroupChatOrchestrator _handle_response methods to remove tool-related content that causes API errors from empty messages.

Moves remaining orchestration-related files to the orchestrations package (were previously missed in the original PR to move things).

Fixes #3705

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines
• All unit tests pass, and I have added new tests where possible
• Is this a breaking change? If yes, add "[BREAKING]" prefix to the title of the PR.

[markwallace-microsoft]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
packages/orchestrations/agent_framework_orchestrations
_base_group_chat_orchestrator.py	170	12	92%	135, 301, 316, 350–352, 356, 375, 436, 480–482
_concurrent.py	193	30	84%	52, 61–62, 70–71, 90–91, 96, 123, 128, 133–134, 140, 162, 172, 179, 347, 350, 378, 434, 446, 485, 487–488, 490, 502–503, 508, 530, 534
_group_chat.py	294	39	86%	173, 336, 343, 372, 383–384, 390, 395, 411, 438–443, 445, 478–481, 483, 488–492, 656, 661, 675, 756, 762, 808, 828, 903–904, 938, 957, 976, 986
_handoff.py	383	57	85%	110–111, 113, 142–143, 165–175, 177, 179, 181, 186, 286, 340, 365, 393, 401–402, 416, 465–466, 498, 545–547, 734, 741, 746, 833, 836, 845–848, 858, 863, 870, 876–879, 914, 919, 1116, 1119, 1127, 1145, 1152, 1227
_magentic.py	620	91	85%	67–76, 81, 85–96, 261, 272, 276, 296, 357, 366, 368, 410, 427, 436–437, 439–441, 443, 454, 596, 598, 638, 686, 722–724, 726, 734–737, 741–744, 787, 814–817, 908, 914, 920, 959, 997, 1026, 1043, 1054, 1108–1109, 1113–1115, 1139, 1160–1161, 1174, 1190, 1212, 1260–1261, 1299–1300, 1459, 1468, 1471, 1476, 1872, 1927, 1942, 1971
_orchestration_request_info.py	54	0	100%
_orchestration_state.py	28	5	82%	20, 28, 68, 85–86
_orchestrator_helpers.py	21	2	90%	90–91
_sequential.py	114	14	87%	74, 167, 185, 196, 202, 239, 241–242, 244, 256–257, 262, 284, 288
TOTAL	16518	2006	87%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
3911	225 💤	0 ❌	0 🔥	1m 5s ⏱️

[Copilot]

Pull request overview

This PR fixes a bug where group chat orchestrators fail with API errors due to empty messages when tool-related content is not properly cleaned from the conversation history. The fix applies the existing clean_conversation_for_handoff utility function to remove tool calls, tool responses, and function approval requests before appending messages to the conversation history or broadcasting them to participants.

Changes:

• Import clean_conversation_for_handoff from _orchestrator_helpers module
• Apply message cleaning in GroupChatOrchestrator._handle_response after processing participant responses
• Apply the same cleaning in AgentBasedGroupChatOrchestrator._handle_response for consistency