[build] replace direct urls with cached ones

backend.native/build.gradle

@@ -18,10 +18,6 @@ buildscript {
    apply from: "$rootDir/gradle/kotlinGradlePlugin.gradle"
    apply plugin: 'project-report'
 
-   repositories {
-       mavenCentral()
-   }
-
    dependencies {
        classpath "com.google.protobuf:protobuf-gradle-plugin:0.8.0"
    }

backend.native/tests/build.gradle

@@ -20,7 +20,9 @@ import org.jetbrains.kotlin.konan.target.KonanTarget
 
 buildscript {
     repositories {
-        mavenCentral()
+        maven {
+            url 'https://cache-redirector.jetbrains.com/maven-central'
+        }
         maven {
             url kotlinCompilerRepo
         }