Fix gradle for Jenkins

.gitignore

@@ -1,5 +1,4 @@
 /.idea/
 /.settings/
 /build/
-/gradle/
 /target/

.gradle/buildOutputCleanup/cache.properties

@@ -1,2 +0,0 @@
-#Mon May 25 16:15:59 CEST 2020
-gradle.version=6.4.1

gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,6 @@
+#Tue May 26 17:58:07 CEST 2020
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.4.1-all.zip
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStorePath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME