Remove vestigial clickhouse.enabled flag

ClickHouse is the only storage backend — there is no alternative.
The enabled flag created a false sense of optionality: setting it to
false would crash on startup because most beans unconditionally depend
on the ClickHouse JdbcTemplate.

Remove all @ConditionalOnProperty annotations gating ClickHouse beans,
the enabled property from application.yml, and the K8s manifest entry.
Also fix old property names in AbstractPostgresIT test config.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cameleer3-server-app/src/main/resources/application.yml

@@ -75,7 +75,6 @@ cameleer:
       oidctlsskipverify: ${CAMELEER_SERVER_SECURITY_OIDCTLSSKIPVERIFY:false}
       corsallowedorigins: ${CAMELEER_SERVER_SECURITY_CORSALLOWEDORIGINS:}
     clickhouse:
-      enabled: ${CAMELEER_SERVER_CLICKHOUSE_ENABLED:true}
       url: ${CAMELEER_SERVER_CLICKHOUSE_URL:jdbc:clickhouse://localhost:8123/cameleer}
       username: ${CAMELEER_SERVER_CLICKHOUSE_USERNAME:default}
       password: ${CAMELEER_SERVER_CLICKHOUSE_PASSWORD:}