Fix console build for GKE (#2713)

We use the $environment property to set the console config. If it is not
given, 'alpha' is used, which has the same effect as 'production'.

TESTED=ran :jetty:copyConsole with
-Penvironment=(sandbox|production|alpha) and checked the resulting js
file.

console-webapp/build.gradle

@@ -40,9 +40,7 @@ task runConsoleWebappUnitTests(type: Exec) {
 task buildConsoleWebapp(type: Exec) {
   workingDir "${consoleDir}/"
   executable 'npm'
-  def configuration = project.hasProperty('configuration') ?
-    project.getProperty('configuration') :
-    'production'
+  def configuration = project.getProperty('configuration')
   args 'run', "build", "--configuration=${configuration}"
   doFirst {
     println "Building console for environment: ${configuration}"

console-webapp/gradle.properties

@@ -0,0 +1 @@
+configuration=production