chore: remove protoc installation in generation check (#13717)

For googleapis/librarian#6558

Author: JoeWang1127

.github/workflows/librarian_generation_check.yaml

@@ -54,14 +54,6 @@ jobs:
         V=$(go run github.com/googleapis/librarian/cmd/librarian@latest config get version)
         echo "Installing librarian version $V"
         go install github.com/googleapis/librarian/cmd/librarian@$V
-    - name: Install protoc
-      run: |
-        set -e
-        VERSION="33.2"
-        curl -fsSL --retry 5 --retry-delay 15 -o /tmp/protoc.zip "https://github.com/protocolbuffers/protobuf/releases/download/v$VERSION/protoc-$VERSION-linux-x86_64.zip"
-        cd /usr/local
-        sudo unzip -o /tmp/protoc.zip
-        protoc --version
     - uses: actions/setup-java@c1e323688fd81a25caa38c78aa6df2d33d3e20d9 # v4
       with:
         java-version: "17"

java-showcase/README.md

@@ -8,7 +8,6 @@ the Showcase API which can communicate with a local Showcase server to perform i
 ## Requirements
 
 * Install [Go](https://go.dev) in your `PATH` (version 1.20 or later).
-* Install the [protoc](https://github.com/protocolbuffers/protobuf/releases) compiler in your `PATH`.
 
 ## Installing the Server
 
@@ -77,7 +76,7 @@ mvn verify -P enable-integration-tests
 This verify check compares the current checked-in files in `java-showcase` against a newly generated client.
 
 ### Prerequisites (One-time Setup)
-Make sure you have **Go** and **protoc** installed and available in your `PATH` (see the [Requirements](#requirements) section), then run the following setup steps from the repository root:
+Make sure you have **Go** installed and available in your `PATH` (see the [Requirements](#requirements) section), then run the following setup steps from the repository root:
 
 ```shell
 # Setup and activate Python virtual environment