chore(eap-spans): Remove unused tables

[phacops]

We're not using those tables anymore.

[github-actions]

This PR has a migration; here is the generated SQL

-- start migrations

-- forward migration events_analytics_platform : 0018_drop_unused_span_tables
Local op: DROP TABLE IF EXISTS spans_str_attrs_2_mv;
Local op: DROP TABLE IF EXISTS spans_num_attrs_2_mv;
Local op: DROP TABLE IF EXISTS spans_str_attrs_2_local;
Local op: DROP TABLE IF EXISTS spans_num_attrs_2_local;
Local op: DROP TABLE IF EXISTS eap_spans_local;
-- end forward migration events_analytics_platform : 0018_drop_unused_span_tables




-- backward migration events_analytics_platform : 0018_drop_unused_span_tables
-- end backward migration events_analytics_platform : 0018_drop_unused_span_tables