Merge pull request #2063 from nextcloud/chore/noid/gradle-repo-optimization

build: Fix/optimize gradle repo configuration

build.gradle

@@ -29,9 +29,7 @@ buildscript {
 
     repositories {
         google()
-        jcenter()
-        maven { url 'https://jitpack.io' }
-        maven { url 'https://plugins.gradle.org/m2/' }
+        gradlePluginPortal()
         mavenCentral()
     }
 
@@ -55,11 +53,9 @@ configurations.all {
 allprojects {
     repositories {
         google()
-        jcenter()
-        maven { url 'https://oss.sonatype.org/content/repositories/snapshots' }
-        maven { url 'https://jitpack.io' }
-        maven { url 'https://maven.google.com' }
         mavenCentral()
+        maven { url 'https://jitpack.io' }
+        gradlePluginPortal() // for jcenter mirroring, remove ASAP
     }
 }