testCoverageEnabled true only in debug.

If you put it in release, this will make the APK / App Bundle debuggable, and Google Play Console will consider it's not signed. Removing this resolved the issue.
https://stackoverflow.com/a/56823288/550384

For compile sign bundle
#3566

android/BOINC/app/build.gradle

@@ -63,14 +63,13 @@ android {
         release {
             minifyEnabled true
             shrinkResources true
-            testCoverageEnabled true
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
         }
         debug {
             // Without this, a build error occurs for debug.
             minifyEnabled true
             debuggable true
-            testCoverageEnabled false
+            testCoverageEnabled true
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
         }
     }