Fix: Delete surplus migration file

htdocs/install/mysql/migration/3.8.0-3.9.0.sql

---
--- Be carefull to requests order.
--- This file must be loaded by calling /install/index.php page
--- when current version is 3.9.0 or higher.
---
--- To rename a table:       ALTER TABLE llx_table RENAME TO llx_table_new;
--- To add a column:         ALTER TABLE llx_table ADD COLUMN newcol varchar(60) NOT NULL DEFAULT '0' AFTER existingcol;
--- To rename a column:      ALTER TABLE llx_table CHANGE COLUMN oldname newname varchar(60);
--- To drop a column:        ALTER TABLE llx_table DROP COLUMN oldname;
--- To change type of field: ALTER TABLE llx_table MODIFY COLUMN name varchar(60);
--- To drop a foreign key:   ALTER TABLE llx_table DROP FOREIGN KEY fk_name;
--- To restrict request to Mysql version x.y use -- VMYSQLx.y
--- To restrict request to Pgsql version x.y use -- VPGSQLx.y
--- To make pk to be auto increment (mysql):    VMYSQL4.3 ALTER TABLE llx_c_shipment_mode CHANGE COLUMN rowid rowid INTEGER NOT NULL AUTO_INCREMENT;
--- To make pk to be auto increment (postgres): VPGSQL8.2 NOT POSSIBLE. MUST DELETE/CREATE TABLE
--- To set a field as NULL:                     VPGSQL8.2 ALTER TABLE llx_table ALTER COLUMN name DROP NOT NULL;
--- To set a field as default NULL:             VPGSQL8.2 ALTER TABLE llx_table ALTER COLUMN name SET DEFAULT NULL;
--- -- VPGSQL8.2 DELETE FROM llx_usergroup_user      WHERE fk_user      NOT IN (SELECT rowid from llx_user);
--- -- VMYSQL4.1 DELETE FROM llx_usergroup_user      WHERE fk_usergroup NOT IN (SELECT rowid from llx_usergroup);
-
--- Fix bad data
-update llx_opensurvey_sondage set format = 'D' where format = 'D+';
-update llx_opensurvey_sondage set format = 'A' where format = 'A+';
-
-INSERT INTO llx_const (name, value, type, note, visible) values ('MAIN_DELAY_EXPENSEREPORTS_TO_PAY','31','chaine','Tolérance de retard avant alerte (en jours) sur les notes de frais impayées',0);
-
-ALTER TABLE llx_accounting_system MODIFY COLUMN pcg_version varchar(32);
-ALTER TABLE llx_accountingaccount MODIFY COLUMN fk_pcg_version varchar(32);
-
-