fix: apps not using desired storageclass in linode

[ElderMatt]

This PR fixes the storage class being used for gitea-valkey and oauth2-proxy, it is now set to linode-block-storage instead of linode-block-storage-retain. Migration has also been added to delete and recreate the pvcs.

[svcAPLBot]

Comparison of Helm chart templating output:

@@ spec.volumeClaimTemplates.v1/PersistentVolumeClaim/valkey-data.spec @@
! + one map entry added:
+ storageClassName: linode-block-storage


@@ spec.volumeClaimTemplates.v1/PersistentVolumeClaim/data.spec @@
! + one map entry added:
+ storageClassName: linode-block-storage

[merll]

I am fine with the main functionality of this branch, but it contains lots of unrelated changes which make it harder to read and later follow up in case someone is looking into old code. I also doubt such changes can be properly QA'ed when they are not used in any recent environment.

I would suggest either

• reverting the unrelated changes
• or removing old migrations entirely. The Istio migration is from 9 months ago and if someone still needs to upgrade a cluster this old, it should be done in smaller increments.