Use the minimum privileges needed

Fixes #291

compose/bootstrap.sql

@@ -1,12 +1,10 @@
 use mysql;
 
-create role if not exists R_DO_IT_ALL;
-grant all on *.* to R_DO_IT_ALL;
+create role if not exists R_MIGRATOR;
+grant alter, create, delete, drop, index, insert, lock tables, select, trigger, update on *.* to R_MIGRATOR;
 create user if not exists msandbox@'%' identified with caching_sha2_password by 'msandbox';
-
-grant R_DO_IT_ALL to msandbox@'%' ;
-set default role R_DO_IT_ALL to msandbox@'%';
-
+grant R_MIGRATOR to msandbox@'%' ;
+set default role R_MIGRATOR to msandbox@'%';
 
 create role if not exists R_REPLICATION;
 grant REPLICATION SLAVE, REPLICATION CLIENT on *.* to R_REPLICATION;