[DOCS] Migrating from grains.get_or_set_hash to sdb.get_or_set_hash

Description
According to the 3005 release note, grains.get_or_set_hash has been removed in favour of sdb.get_or_set_hash (#61691).

I've updated every occurrences of salt['grains.get_or_set_hash'](...) to salt['sdb.get_or_set_hash'](...) in the state tree. When applying it via sudo salt-call --local state.apply (note that I'm using salt in masterless mode), in place of the generated hash I had before, I'm now obtaining a False value.

Even the example from the documentation is failing to generate and return a value:

sudo salt-call --local sdb.get_or_set_hash 'SECRET_KEY' 50
local:
    False

I've tried to setup another database but none of the existing drivers seems to implement the .get_or_set_hash method.

Another question: previously, I was sharing the grains file across the nodes of the cluster trough a glusterfs mount point in order to share data between masterless minions (master-minion model is not suitable in this specific situation); when using default sdb database (documentation is unclear if a default database even exists or if one must necessarily define one with a specific driver), where is the data-storage located?

Start by reading the 3005 release note, the sdb.get_or_set_hash reference, SDB configuration, and the listed SDB drivers. Reproduce the documented salt-call command, then clarify the migration behavior, default database configuration, and data-storage location in the relevant documentation, or document the correct limitation if the example is invalid.