chore: content_script_version_2: add simple protection and rm messages_backup if exists

[Ivansete-status]

Description

This is aimed to add a simple protection. If the messages_backup exists, then delete it.
Notice that this would only protect the users that are now running a version lower than v0.26.0, and update their nodes to a version >= v0.27.0.

EDITED: In further migrations, we might need to implement a rollback feature that should trigger if an error occurs within the migration, as suggested by @SionoiS some time ago.

How to test

1. Run a node with store protocol enabled for a while and version ' v0.25.0`. Wait until some messages are written (I've tested it with ~3.6GB database.)
2. Run a node from this branch and

Issue

closes waku-org/nwaku-compose#75

[SionoiS]

Am I understanding correctly that this would fix the case where the migration errors before DROP TABLE IF EXISTS messages_backup; at the end?

If yes then it would fix the problem but if it fails again then the backup is lost no?

Up to you if loosing the backup is an acceptable risk.

[NagyZoltanPeter]

LGTM!

[Ivansete-status]

Am I understanding correctly that this would fix the case where the migration errors before DROP TABLE IF EXISTS messages_backup; at the end?

If yes then it would fix the problem but if it fails again then the backup is lost no?

Up to you if loosing the backup is an acceptable risk.

Cool thanks! I adapted it according to your advise 🥳
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