Enable build cache (DataDog/dd-trace-java#1607)

Author: mar-kolya

.circleci/config.yml

@@ -17,7 +17,7 @@ cache_keys: &cache_keys
 parameters:
   gradle_flags:
     type: string
-    default: "--build-cache --parallel --stacktrace --no-daemon"
+    default: "--stacktrace --no-daemon"
 
 jobs:
   build:

gradle.properties

@@ -1 +1,4 @@
+org.gradle.parallel=true
+org.gradle.caching=true
+
 org.gradle.jvmargs=-XX:MaxMetaspaceSize=1g