Update references in CI values file from redis to valkey for the built-in Valkey

[benbz]

#1559 deliberately did not touch the CI value files so as to prove the merging of values from redis -> valkey worked.

Now that this has been done, we do this rename. This should be a no-op and the end of the updating of things for the built-in Valkey.

Absent is any renaming of properties for external Redis/Valkey. The files in charts/matrix-stack/ci with redis in their name relate to an external Redis/Valkey and so should not be renamed yet

[github-actions]

dyff of changes in rendered templates of CI manifests

No changes in rendered templates

[gaelgatelement]

 grep -rnw redis: charts/matrix-stack/ci/fragments/
charts/matrix-stack/ci/fragments/matrix-rtc-redis-secrets-in-helm.yaml:8:    redis:
charts/matrix-stack/ci/fragments/synapse-redis.yaml:6:  redis:
charts/matrix-stack/ci/fragments/matrix-rtc-redis-secrets-externally.yaml:8:    redis:
charts/matrix-stack/ci/fragments/synapse-redis-secrets-in-helm.yaml:6:  redis:
charts/matrix-stack/ci/fragments/hookshot-redis-secrets-externally.yaml:6:  redis:
charts/matrix-stack/ci/fragments/matrix-rtc-redis.yaml:8:    redis:
charts/matrix-stack/ci/fragments/synapse-redis-secrets-externally.yaml:6:  redis:
charts/matrix-stack/ci/fragments/hookshot-redis.yaml:6:  redis:
charts/matrix-stack/ci/fragments/hookshot-redis-secrets-in-helm.yaml:6:  redis:

Is that on purpose?

[benbz]

 grep -rnw redis: charts/matrix-stack/ci/fragments/
charts/matrix-stack/ci/fragments/matrix-rtc-redis-secrets-in-helm.yaml:8:    redis:
charts/matrix-stack/ci/fragments/synapse-redis.yaml:6:  redis:
charts/matrix-stack/ci/fragments/matrix-rtc-redis-secrets-externally.yaml:8:    redis:
charts/matrix-stack/ci/fragments/synapse-redis-secrets-in-helm.yaml:6:  redis:
charts/matrix-stack/ci/fragments/hookshot-redis-secrets-externally.yaml:6:  redis:
charts/matrix-stack/ci/fragments/matrix-rtc-redis.yaml:8:    redis:
charts/matrix-stack/ci/fragments/synapse-redis-secrets-externally.yaml:6:  redis:
charts/matrix-stack/ci/fragments/hookshot-redis.yaml:6:  redis:
charts/matrix-stack/ci/fragments/hookshot-redis-secrets-in-helm.yaml:6:  redis:

Is that on purpose?

Yes as per the PR body:

Absent is any renaming of properties for external Redis/Valkey. The files in charts/matrix-stack/ci with redis in their name relate to an external Redis/Valkey and so should not be renamed yet