Enable coverage only in CI (#4068)

Enable coverage only in CI

.drone.yml

@@ -53,6 +53,7 @@ steps:
         from_secret: GIT_USERNAME
       GIT_TOKEN:
         from_secret: GIT_TOKEN
+      ORG_GRADLE_PROJECT_coverage: ''
     commands:
       - ./gradlew assembleGplay
       - emulator -avd android-27 -no-window -no-audio &

build.gradle

@@ -125,7 +125,7 @@ android {
 
         buildTypes {
             debug {
-                testCoverageEnabled true
+                testCoverageEnabled (project.hasProperty('coverage') ? true : false)
             }
         }