Bulk upgrade managed integrations

Upgrade multiple managed integrations to their installed package version, migrating each package policy's config onto the new schema. Always returns 200 with a per-policy result array; a missing id, or an id that is not a managed integration, is reported as a per-item failure (success: false + statusCode) without failing the batch, so valid ids are still upgraded. A successful result means the policy's saved object was upgraded, while the agentless deployment is reconciled asynchronously in the background. Policies already at the installed version are a genuine no-op: they still report success: true (calls stay idempotent) but nothing is re-persisted or redeployed. Note: agent-policy-level agentless settings (resources, ownership tags) are not re-derived from the new package version — use the update (PUT) endpoint for those.