[ATTRIBUTES] Avoid calling InitializeTables() on every tabular create operation

[zaeema-n]

Problem

InitializeTables() is invoked in the tabular create flow, so each create request performs schema-init checks for global metadata tables (entity_attributes, attribute_schemas).

Why this is bad

• Adds unnecessary DB roundtrips on every create
• Increases request latency and DB load
• Mixes one-time infrastructure bootstrap with hot-path request handling

Current behavior
Per-request create path calls InitializeTables().

Expected behavior
InitializeTables() should run once at service startup/bootstrap, not per create request.

Proposed fix

1. Remove InitializeTables() call from tabular CreateResolve request path
2. Call InitializeTables() once during core startup after Postgres repo creation
3. Ensure test/e2e bootstrap handles DB-reset scenarios (so startup-only init remains reliable)

Acceptance criteria

• No InitializeTables() call in per-request tabular create path
• Startup fails fast if initialization fails
• Create requests no longer perform schema-init overhead
• E2E still passes with explicit bootstrap/restart after DB reset

Relevant files

• opengin/core-api/engine/attribute_resolver.go
• opengin/core-api/cmd/server/service.go
• opengin/core-api/db/repository/postgres/postgres_client.go