Bump dependent cube versions when upstream metric/dimension changes

[shangyian]

Summary

When a metric or dimension node's query is updated, downstream cubes were silently excluded from propagation. Thus, a cube's element list doesn't change when an upstream metric's SQL changes, so the diff-based update path produces no version bump. Any consumer that gates workflow regeneration on cube version IDs would see no change and skip updating, leaving stale SQL in production.

The fixes include:

• _propagate_update_downstream now fetches all downstreams with include_cubes=True, revalidates non-cube nodes as before, then calls bump_cube_versions for downstream cubes.
• bump_cube_versions is the single shared implementation: creates a new minor revision for each cube via create_cube_node_revision, which re-validates and rebuilds columns correctly.

Deduplication is handled by the existing visited-node sets in both propagation paths.

Test Plan

• PR has an associated issue: #
• make check passes
• make test shows 100% unit test coverage

Deployment Plan

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