For #11392: Rename Installation ping to FirstSession

[sblatz]

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[liuche]

That works for me, renaming of the session.

May need to rebase this off master to get the codecov fix.

[liuche]

@sblatz I also need a PR against the releases/78.0.0 branch with this change, PLUS the removing GAID change. I'm currently making the branding change in #11872 + codecov breakage fix, so you could either wait for that to land and then rebase, or cherry-pick the codecov commit that fixes the broken CI (#11928 )