Fix AssistantAgent Tool Call Behavior #2246

Job	Run time
format	49s
pyright (./packages/autogen-core)	56s
mypy (./packages/autogen-core)	1m 54s
pyright (./packages/autogen-magentic-one)	1m 12s
mypy (./packages/autogen-magentic-one)	1m 9s
pyright (./packages/agbench)	1m 3s
mypy (./packages/agbench)	1m 2s
pyright (./packages/autogen-ext)	1m 3s
docs (./packages/autogen-core)	1m 27s
mypy (./packages/autogen-ext)	1m 40s
check-proto-changes-python	1m 26s
pyright (./packages/autogen-agentchat)	1m 10s
mypy (./packages/autogen-agentchat)	1m 17s
docs-example-check (./packages/autogen-core)	2m 18s
lint	50s
test (./packages/autogen-core)	1m 1s
test (./packages/autogen-magentic-one)	1m 33s
test (./packages/autogen-ext)	2m 21s
test (./packages/autogen-agentchat)	59s
	25m 10s

Provide feedback