chore(tvix/[ca]store): bump bigtable_rs

This bumps bigtable_rs to
liufuyang/bigtable_rs#86, allowing us to drop
our second set of prost/tonic/http/axum crates.

Change-Id: I70f9150289c3e8611ebe8a7d99490e3dfd085a6e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12384
Tested-by: BuildkiteCI
Reviewed-by: Connor Brewster <cbrewster@hey.com>
Autosubmit: flokli <flokli@flokli.de>