Incorrect replica/keeper validation logic — checks `keeper.enabled` instead of actual replica count

[Elmo33]

Updating shards fails with:

Error: UPGRADE FAILED: execution error at (clickhouse/templates/chi.yaml:218:3): When 'clickhouse.replicasCount' > 1, either 'keeper.enabled' must be true or 'clickhouse.keeper.host' must be set.

The logic is flawed.

Current behavior:

• The chart only triggers this validation when keeper.enabled: false.
• If keeper.enabled: true but no actual replicaCount is set (or is not >=1), the validation silently passes.
• This results in a deployment where keeper is “enabled” but the chart never configures any keeper hosts, causing runtime failures like:

Exception: Unexpected error creating database:
Coordination::Exception: Cannot resolve any of provided ZooKeeper hosts due to DNS error. (KEEPER_EXCEPTION)
(query: CREATE DATABASE IF NOT EXISTS test_replication_db ON CLUSTER '{cluster}')

Example values causing failure:

keeper:
  enabled: true

No replicaCount or keeper hosts → chart pretends everything is fine → ClickHouse blows up because it cannot resolve ZK hosts.

Expected behavior:
The validation should check:

• clickhouse.replicasCount >= 1
• AND if replicas > 1 → keeper must be properly configured (enabled and with valid hosts), not merely "enabled: true".