fix(bigframes): update GeminiTextGenerator default model to gemini-2.5-flash - #18060

fix(bigframes): update GeminiTextGenerator default model to gemini-2.5-flash#18060

shuoweil wants to merge 4 commits into

maingoogleapis/google-cloud-python:mainfrom

shuowei-default-model-gemini-2-5-flashgoogleapis/google-cloud-python:shuowei-default-model-gemini-2-5-flashCopy head branch name to clipboard