File google-services.json is missing. Plugin did not search in all flavor locations.

**Describe the bug**
Issue is that plugin can't find google-services.json,
but in the list of search locations I don't see some of the source sets for specific flavor
in multi flavor project.

So to give an example. Let's say I have this build variant: flavorTest/release.

These are the searched locations:

**Actual behaviour**
"src/release",
"src/flavorRelease",
"src/flavor",
"src/flavor/release",
"src/release/flavorTest",
"src/flavorTest",
"src/flavorTestRelease",
"src/flavor/test/release",
"src/flavor/testRelease"

**Expected behaviour**
"src/flavorTest/release",
"src/release/flavorTest",
"src/flavor/release",
"src/test/release",
"src/flavorTest",
"src/release",
"src/flavorTestRelease",
"src/flavor",
"src/flavorRelease",
"src/test",
"src/testRelease"

**Desktop (please complete the following information):**
- Gradle version: 4.8.1
- Android Studio version: 3.3 RC1
- Plugin name and version: com.google.gms:google-services:4.2.0

*Context*
Second flavor dimension alone is missing from search locations, so it is impossible to use it to store google-services.json.