remove old proto workflow (#9167)

.github/workflows/proto.yml

@@ -1,22 +0,0 @@
-name: Protobuf
-# Protobuf runs buf (https://buf.build/) lint and check-breakage
-# This workflow is only run when a .proto file has been modified
-on:
-  pull_request:
-    paths:
-      - "**.proto"
-jobs:
-  proto-lint:
-    runs-on: ubuntu-latest
-    timeout-minutes: 4
-    steps:
-      - uses: actions/checkout@v3
-      - name: lint
-        run: make proto-lint
-  proto-breakage:
-    runs-on: ubuntu-latest
-    timeout-minutes: 4
-    steps:
-      - uses: actions/checkout@v3
-      - name: check-breakage
-        run: make proto-check-breaking-ci