proto: buf for everything (#5650)

## Description

- remove installation of protoc
- use buf protoc to generate proto stubs

prior to approving could someone test locally. I restarted my docker instance and its been stuck for 20+ minutes

Closes: #XXX

scripts/protocgen.sh

@@ -4,7 +4,7 @@ set -eo pipefail
 
 proto_dirs=$(find ./proto -path -prune -o -name '*.proto' -print0 | xargs -0 -n1 dirname | sort | uniq)
 for dir in $proto_dirs; do
-  protoc \
+  buf protoc \
   -I "proto" \
   -I "third_party/proto" \
   --gogofaster_out=\