Simplify cache-redirector script apply method

Now it could be only be applied inside settings file pluginManagement
block. This will update both settings repositories and all projects in
the repo with cache redirection settings.

kotlin-native/backend.native/tests/build.gradle

@@ -15,10 +15,7 @@ import static org.jetbrains.kotlin.konan.target.Architecture.*
 
 buildscript {
     repositories {
-        if (UtilsKt.getCacheRedirectorEnabled(project))
-            maven { url 'https://cache-redirector.jetbrains.com/maven-central'}
-        else
-            mavenCentral()
+        mavenCentral()
 
         maven {
             url project.bootstrapKotlinRepo