fix: fix faulty shutdownHook definition in the Config-Schema

In the config-service of the api-server the configuration value for
"shutdownHook" is not getting applied due to an issue in the reducer of
the newExampleConfigEnv(). The reducer is not populating the
shutdownHook configuration based on a faulty Config-Schema definition
for the shutdownHook where "arg" and "env" are missing.

Closes: #1648
Signed-off-by: Michael Courtin <michael.courtin@accenture.com>

packages/cactus-cmd-api-server/src/main/typescript/config/config-service.ts

@@ -421,6 +421,8 @@ export class ConfigService {
           "(which is the default behavior). You will want to turn this off if you are embedding " +
           "the API server in your own application and would like to stop the API server from " +
           "meddling in the OS process signal handling when you take care of it yourself in your own code.",
+        env: "ENABLE_SHUTDOWN_HOOK",
+        arg: "enable-shutdown-hook",
         format: Boolean,
         default: true,
       },