Enable backup system only if SeedVault fork is installed

• /e/ version: 0.12 (pie an q)

Summary

We are working on intregrating SeedVault as our default backup solution.

With e/os/android_vendor_lineage!48 (merged), we set SeedVault as the default backup transport (here).

As Backup system is currently under development and test, it is only included on test builds.

Description

What is the current behavior?

On test build, everything looks fine.

On dev and stable builds, as we do not embed SeedVault, it shows a Google Message.

What is the improved behavior?

Enable Backup and SeedVault as default backup transport only for test builds.

What does it bring?

Avoid confusion from user.

Examples

Validation