Use Indexer release for all but dev configuration

[fabrice102]

Problem

Currently, sandbox recompiles the indexer from the master branch even for the default release configuration.
This makes sandbox slower to start (compared to downloading an executable) and running a potentially non-fully stable software.

Solution

Use the latest stable release from indexer.
This change may be simpler if the indexer is published as a Debian package.

Urgency

Nice to have.

[fabrice102]

This seems to be related to #37

[winder]

Blocked by https://github.com/algorand/go-algorand-internal/issues/623