Use TTL for matviews regardless of --enterprise

[javier]

Summary

• QuestDB does not yet support STORAGE POLICY on materialized views, so matviews always use TTL (in both OSS and enterprise mode).
• Tables continue to use STORAGE POLICY when --enterprise=true and --short_ttl=true.
• New helper mv_retention_clause() mirrors retention_clause() but ignores the enterprise_policy argument. Keeping the matching signature means the 11 matview CREATE statements stay untouched.
• The previous binding is kept as a commented line at the rc lambda so reverting is a one-line swap once matview storage policies land.

Test plan

• Run with --short_ttl=true --enterprise=false: matviews get TTL, tables get TTL.
• Run with --short_ttl=true --enterprise=true: matviews get TTL, tables get STORAGE POLICY.
• Run with --short_ttl=false: neither tables nor matviews get a retention clause.