fix(interactions): avoid duplicate User-Agent headers#2313

MukundaKatta wants to merge 3 commits intogoogleapis:maingoogleapis/python-genai:mainfrom

MukundaKatta:codex/python-genai-interactions-user-agentMukundaKatta/python-genai:codex/python-genai-interactions-user-agentCopy head branch name to clipboard