docs(adr): ADR no. 10 - Backup Bucket Usage

[deer-wmde]

A proposal to use GCP buckets differently, to avoid situations where we have zero logical backups.

An example of how this could look like can be currently seen in the staging backup bucket: https://console.cloud.google.com/storage/browser/wikibase-dev-sql-backup

Another approach to tackle this and logical SQL backups in general could be to revisit ADR no. 1 since meanwhile the feature availability reached GA

[deer-wmde]

Concern raised in daily "but is there no risk we quickly overwrite the backup with 7 different nearly empty/corrupt versions?"

[deer-wmde]

Concern raised in daily "but is there no risk we quickly overwrite the backup with 7 different nearly empty/corrupt versions?"

I think that concern is very valid and makes me think that the approach written down in this ADR is not much worth to pursue then.

The integrity of the backups is also not checked in any way with the current state of things, but if both approaches can't deal with that we're probably just better off increasing the current retainment period and hope it will work out.

Thus this PR can be closed if no-one has an idea to counter this issue

edit: actually, should the ADR be merged with the status Rejected ? probably too confusing as so far we are only accommodating Accepted ADRs ...

[deer-wmde]

Concern raised in daily "but is there no risk we quickly overwrite the backup with 7 different nearly empty/corrupt versions?"

Today I remembered that we have a check for that in place, so maybe this ADR would still be helpful to implement.

https://github.com/wmde/wbaas-backup/blob/main/src/validate_expected_files.sh