web: Add the instance_name configuration key

This allows to build properly the same instance of lister for the routine which schedules successful save code now origins (in the scheduler).

Related to swh-web#1524 (closed)

Test Plan

doco up -d with the proper override

$ psql service=swh-scheduler-dev # <- proper configuration to do that
swh-scheduler=# \conninfo
You are connected to database "swh-scheduler" as user "postgres" on host "localhost" (address "::1") at port "5433".
swh-scheduler=# select * from listers;
+--------------------------------------+---------------+-------------------------------------+-------------------------------+---------------+-------------------------------+
|                  id                  |     name      |            instance_name            |            created            | current_state |            updated            |
+--------------------------------------+---------------+-------------------------------------+-------------------------------+---------------+-------------------------------+
| f1e2de80-7575-4ea0-95b2-359b82cc860f | save-code-now | archive-docker.softwareheritage.org | 2021-06-15 14:12:42.541672+00 | {}            | 2021-06-15 14:12:42.541672+00 |
+--------------------------------------+---------------+-------------------------------------+-------------------------------+---------------+-------------------------------+
(1 row)

swh-scheduler=# select * from listed_origins ;
+--------------------------------------+---------------------------------------------+------------+------------------------+---------+-------------------------------+-------------------------------+-------------+
|              lister_id               |                     url                     | visit_type | extra_loader_arguments | enabled |          first_seen           |           last_seen           | last_update |
+--------------------------------------+---------------------------------------------+------------+------------------------+---------+-------------------------------+-------------------------------+-------------+
| f1e2de80-7575-4ea0-95b2-359b82cc860f | https://github.com/zapletnev/eclipse-regexp | git        | {}                     | t       | 2021-06-15 15:12:12.495264+00 | 2021-06-15 15:12:12.495264+00 | (null)      |
+--------------------------------------+---------------------------------------------+------------+------------------------+---------+-------------------------------+-------------------------------+-------------+

in-progress

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Migrated from D5873 (view on Phabricator)