Remove /plugins-release and /plugins-snapshot from build

Those repositories now need authentication, and we do not actually need them, the dependencies can be resolved from Maven Central

Closes gh-13245

(cherry picked from commit 663f5cf76b8e8a8cd4b4f33c6c31ccb97e3661ef)

build.gradle

@@ -9,7 +9,6 @@ buildscript {
 		classpath "com.netflix.nebula:nebula-project-plugin:8.2.0"
 	}
 	repositories {
-		maven { url 'https://repo.spring.io/plugins-snapshot' }
 		maven { url 'https://plugins.gradle.org/m2/' }
 	}
 }

buildSrc/build.gradle

@@ -10,7 +10,6 @@ sourceCompatibility = 1.8
 repositories {
 	gradlePluginPortal()
 	mavenCentral()
-	maven { url 'https://repo.spring.io/plugins-release/' }
 }
 
 sourceSets {

settings.gradle

@@ -1,7 +1,6 @@
 pluginManagement {
 	repositories {
 		gradlePluginPortal()
-		maven { url 'https://repo.spring.io/plugins-release' }
 	}
 }