Relay migrated simulation schema services from flow360-schema

[benflexcompute]

What changed

• converted more of flow360/component/simulation/ into thin relays over schema-owned implementations
• removed duplicate client implementations for migrated schema-owned logic, including validation service entry points, schema service helpers, updater helpers, conversion helpers, utils, and services_utils
• removed duplicate client tests that now belong to schema ownership in the paired schema PR

Why

The migration target is for the client to keep runtime-only responsibilities such as translator orchestration, web API code, BET wrappers, and unit-switching, while schema owns Pydantic behavior, validation, and deserialization.

This PR is the same client migration batch, but re-rooted cleanly onto main instead of BenY/CentralizedSchema.

Impact

• client-side duplication is reduced substantially in this batch
• schema-owned tests now live with the code they validate
• the remaining client work is more clearly limited to runtime orchestration and a smaller set of residual case-by-case migrations

Validation

• python -m py_compile flow360/component/simulation/services.py flow360/component/simulation/services_utils.py flow360/component/simulation/conversion.py flow360/component/simulation/utils.py flow360/component/simulation/framework/updater.py flow360/component/simulation/framework/updater_functions.py flow360/component/simulation/framework/updater_utils.py flow360/component/simulation/user_code/core/types.py
• targeted schema-side test suites were run in the paired schema PR for the migrated behavior
• targeted client smoke tests were run during the migration for relay boundaries, but a full client pytest run was not used for this batch because the local client environment still had an older installed flow360-schema package during development

Paired Schema PR

• flexcompute/flex#11404

Remaining Work From Plan

• audit and shrink legacy unit_system.py / exposed_units.py only after confirming real remaining consumers
• keep translator, BET request wrappers, web API code, process-json generation, and unit-switching orchestration on the client side
• continue the remaining case-by-case cleanup in client tests and any residual helper boundaries, especially the still-mixed portions of tests/simulation/params/test_validators_params.py and tests/simulation/services/test_selector_expansion_validators.py
• leave draft/project/web/runtime workflow tests on the client side unless a specific case proves to be pure schema behavior

Follow-up

This PR intentionally supersedes #1998 for review against main. The remaining items should be finished in a follow-up PR rather than expanding this one further.

[benflexcompute]

Superseded by #2000, which is the clean re-rooted version against current main.