build,test: make test-grpc-packages pass again

No need to install `@grpc/proto-loader` in Makefile's
`test-agents-prereqs` target.

Author: santigimeno

Makefile

@@ -1696,7 +1696,7 @@ test-agents-prereqs:
 	env npm_config_nodedir=$(PWD) $(NODE) ./deps/npm install nan@latest --no-save --no-package-lock --prefix test/common/nsolid-zmq-agent/node_modules/zeromq
 	env npm_config_nodedir=$(PWD) $(NODE) ./deps/npm run build:libzmq --prefix test/common/nsolid-zmq-agent/node_modules/zeromq
 	env npm_config_nodedir=$(PWD) $(NODE) ./deps/npm install @opentelemetry/otlp-proto-exporter-base @grpc/grpc-js @grpc/proto-loader --prefix test/common/nsolid-otlp-agent --no-save --no-package-lock
-	env npm_config_nodedir=$(PWD) $(NODE) ./deps/npm install @grpc/grpc-js @grpc/proto-loader --prefix test/common/nsolid-grpc-agent --no-save --no-package-lock
+	env npm_config_nodedir=$(PWD) $(NODE) ./deps/npm install @grpc/grpc-js --prefix test/common/nsolid-grpc-agent --no-save --no-package-lock
 
 .PHONY: test-agents-prereqs-clean
 test-agents-prereqs-clean: