feat(eap-items): drop attributes_array JSON column from distributed tables

[onewland]

Reprise of #8231, which was reverted (451f9eb): dropping attributes_array from the downsample local MergeTree tables triggered a full part rewrite even though the column was empty, which is unacceptable in customer-facing environments.

This version (migration 0062_drop_attributes_array_json_from_dist) drops the attributes_array JSON column (added in 0050, superseded by the typed attributes_array_{string,int,float,bool} map columns from 0059) from distributed tables only — a metadata-only change with no data rewrites:

• eap_items_1_dist + downsample _dist tables (EVENTS_ANALYTICS_PLATFORM)
• eap_items_1_dist_ro + downsample _dist_ro tables (EVENTS_ANALYTICS_PLATFORM_RO, inherited via CREATE TABLE ... AS in 0056)

Notes:

• All local (MergeTree) tables keep the column. The downsample materialized views never projected attributes_array (verified across all MV versions mv_1–mv_9), so the column holds only default values there and nothing references it.
• No view regeneration needed. Backwards ops re-add the column with its original 0050 definition.
• Consumer stopped writing the column in Stop writing to the attributes_array column in the EAP consumer #8179 (2026-07-14); with ~90d retention, the last rows that could contain data in eap_items_1_local age out around mid-October 2026, after which the local-table column could be revisited.

[github-actions]

This PR has a migration; here is the generated SQL for ./snuba/migrations/groups.py ()

-- start migrations

-- forward migration events_analytics_platform : 0062_drop_attributes_array_json_from_dist
Distributed op: ALTER TABLE eap_items_1_dist ON CLUSTER 'cluster_one_sh' DROP COLUMN IF EXISTS attributes_array;
Distributed op: ALTER TABLE eap_items_1_downsample_8_dist ON CLUSTER 'cluster_one_sh' DROP COLUMN IF EXISTS attributes_array;
Distributed op: ALTER TABLE eap_items_1_downsample_64_dist ON CLUSTER 'cluster_one_sh' DROP COLUMN IF EXISTS attributes_array;
Distributed op: ALTER TABLE eap_items_1_downsample_512_dist ON CLUSTER 'cluster_one_sh' DROP COLUMN IF EXISTS attributes_array;
Distributed op: ALTER TABLE eap_items_1_dist_ro ON CLUSTER 'cluster_one_sh' DROP COLUMN IF EXISTS attributes_array;
Distributed op: ALTER TABLE eap_items_1_downsample_8_dist_ro ON CLUSTER 'cluster_one_sh' DROP COLUMN IF EXISTS attributes_array;
Distributed op: ALTER TABLE eap_items_1_downsample_64_dist_ro ON CLUSTER 'cluster_one_sh' DROP COLUMN IF EXISTS attributes_array;
Distributed op: ALTER TABLE eap_items_1_downsample_512_dist_ro ON CLUSTER 'cluster_one_sh' DROP COLUMN IF EXISTS attributes_array;
-- end forward migration events_analytics_platform : 0062_drop_attributes_array_json_from_dist




-- backward migration events_analytics_platform : 0062_drop_attributes_array_json_from_dist
Distributed op: ALTER TABLE eap_items_1_downsample_512_dist_ro ON CLUSTER 'cluster_one_sh' ADD COLUMN IF NOT EXISTS attributes_array JSON(max_dynamic_paths=128) CODEC (ZSTD(1)) AFTER attributes_float_39;
Distributed op: ALTER TABLE eap_items_1_downsample_64_dist_ro ON CLUSTER 'cluster_one_sh' ADD COLUMN IF NOT EXISTS attributes_array JSON(max_dynamic_paths=128) CODEC (ZSTD(1)) AFTER attributes_float_39;
Distributed op: ALTER TABLE eap_items_1_downsample_8_dist_ro ON CLUSTER 'cluster_one_sh' ADD COLUMN IF NOT EXISTS attributes_array JSON(max_dynamic_paths=128) CODEC (ZSTD(1)) AFTER attributes_float_39;
Distributed op: ALTER TABLE eap_items_1_dist_ro ON CLUSTER 'cluster_one_sh' ADD COLUMN IF NOT EXISTS attributes_array JSON(max_dynamic_paths=128) CODEC (ZSTD(1)) AFTER attributes_float_39;
Distributed op: ALTER TABLE eap_items_1_downsample_512_dist ON CLUSTER 'cluster_one_sh' ADD COLUMN IF NOT EXISTS attributes_array JSON(max_dynamic_paths=128) CODEC (ZSTD(1)) AFTER attributes_float_39;
Distributed op: ALTER TABLE eap_items_1_downsample_64_dist ON CLUSTER 'cluster_one_sh' ADD COLUMN IF NOT EXISTS attributes_array JSON(max_dynamic_paths=128) CODEC (ZSTD(1)) AFTER attributes_float_39;
Distributed op: ALTER TABLE eap_items_1_downsample_8_dist ON CLUSTER 'cluster_one_sh' ADD COLUMN IF NOT EXISTS attributes_array JSON(max_dynamic_paths=128) CODEC (ZSTD(1)) AFTER attributes_float_39;
Distributed op: ALTER TABLE eap_items_1_dist ON CLUSTER 'cluster_one_sh' ADD COLUMN IF NOT EXISTS attributes_array JSON(max_dynamic_paths=128) CODEC (ZSTD(1)) AFTER attributes_float_39;
-- end backward migration events_analytics_platform : 0062_drop_attributes_array_json_from_dist

[phacops]

Let's not add the column back in case we need to go backwards.