chore: Set grpc-opentelemetry dep to test scope

Author: lqiu96

java-showcase/gapic-showcase/pom.xml

@@ -100,6 +100,7 @@
     <dependency>
       <groupId>io.grpc</groupId>
       <artifactId>grpc-opentelemetry</artifactId>
+      <scope>test</scope>
     </dependency>
     <dependency>
       <groupId>com.google.api.grpc</groupId>