Ibexa installer update scripts do not take into account different editions

Steps:

1. Install Ibexa Content v4.1.5.
2. Follow update steps to Ibexa Content v4.2.0.
3. Examine result of "Update the database" step.

Actual result: Error occurs

psql:vendor/ibexa/installer/upgrade/db/postgresql/ibexa-4.1.latest-to-4.2.0.sql:244: ERROR:  relation "ibexa_segment_user_map" does not exist
LINE 1: DELETE FROM "ibexa_segment_user_map" su

Expected result: Update scripts are separated per edition OR migration tool exists which selects queries appropriate for given edition.

Remarks: Affects MySQL update script also.