fix: Do not upload/read files when path starts with gs://

[pawelpasterz]

Fixes #1971

When user provides gs:// path in other-files we should not upload it again.

Files.readAllBytes(Paths.get(file))

will never succeed when the path starts with gs://

Test Plan

How do we know the code works?

1. flank test bucket
2. run ./gradlew flankFullRun
3. prepare config with:

   other-files:
       /sdcard/[some file name]: gs://[path to file uploaded to the bucket, you can reuse existing one]
   

4. run tests
5. go to result bucket and check if there is a file from config under /artifacts/sdcard/ path

[github-actions]

Timestamp: 2021-07-14 12:23:20
Buildscan url for ubuntu-workflow run 1030192163
https://gradle.com/s/466x2yln5wzzm

[piotradamczyk5]

👌

[Sloox]

@flank-it

[github-actions]

Integration tests were triggered at 2021-07-14 12:17:19, you can track progress here