CSUB-2030: Parametrize git-lfs checkout for native builds

[atodorov]

when running the majority of test jobs we don't really need chainspecs so don't checkout/build them in.

[cursor]

PR Summary

Medium Risk
Changes the reusable build-native.yml workflow interface and updates multiple callers, so any missed caller or incorrect LFS setting could break CI builds or omit required large files.

Overview
Adds a git-lfs-checkout input to the reusable native build workflow (build-native.yml) and wires it into both checkout paths so LFS fetching can be enabled/disabled per job.

Updates all build-native.yml callers (CI, benchmarks, proof-gen, chainspec, release, runtime-upgrade, metadata rebuild) to explicitly set git-lfs-checkout, typically disabling it for most test builds and enabling it for chainspec/release/runtime-upgrade builds.

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