Convert Redis formula to Valkey formula

[tacerus]

https://lists.opensuse.org/archives/list/factory@lists.opensuse.org/thread/6DXKWZHBPEEHBWR6BQYYTLFLAISUZM6Z/

I guess copying redis-formula to valkey-formula and replacing all occurrences of "redis" with "valkey" should suffice.

Ideally then just applying valkey on top of redis on a minion should not conflict with what https://build.opensuse.org/projects/server:database/packages/valkey/files/migrate_redis_to_valkey.bash?expand=1 is doing upon dup.

[tacerus]

Now that redis is back in Factory we should keep the redis formula / its functionality, and migration functionality is no longer needed. Maybe the "redis" strings in the redis formula could simply be moved to a variable allowing for a pillar toggle switching between "redis" and "valkey".