Only send `Stop` event at end of google completion request (#29885)

I don't think this makes much of a difference in current use, but this
more closely matches other providers and cleans up the "Response"
section of eval markdown output

Release Notes:

- N/A
a0895a6ed8Michael Sloan committed on 5/4/2025, 8:23:13 PM· committed by GitHubparentbb82d9c
1 file changedLine totals unavailable