feat(preprod): Reland quota check

[chromy]

• Reapply "feat(preprod): Check quota available in preprod assemble" (Revert "feat(preprod): Check quota available in preprod assemble" #106518)
• Reapply "feat(preprod): Check quota and run only available features" (Revert "feat(preprod): Check quota and run only available features" #106517)
• Move quota checks behind new flag preprod-enforce-quota

[cursor]

Cursor Bugbot has reviewed your changes and found 2 potential issues.

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[cursor]

Size metrics created without checking SIZE_ANALYSIS quota

Medium Severity

The diff removes the TODO comment # TODO(preprod): add gating to only create if has quota but doesn't implement the gating. PreprodArtifactSizeMetrics is created unconditionally in PENDING state, even when the organization only has INSTALLABLE_BUILD quota and not SIZE_ANALYSIS quota. Since size analysis won't run without quota, these records will remain stuck in PENDING state forever. The org_has_size_quota variable is already computed (line 210) but isn't used to gate the size metrics creation.