[IMP] yodoo_apps_website: enqueue up to 10 git sources per scheduler run
Stacked MR: the target is 18.0-yodoo_apps_website-fix-github-auth, so this merges after that MR.
What changed: the git source scheduler in yodoo_apps_website no longer carries a copy of the yodoo_apps_git_source cron body. It overrides the new hooks of yodoo_apps_git_source instead. GitHub sources are excluded from a run when GitHub is unreachable (one connect() per run). The number of sync tasks enqueued per run comes from the system parameter yodoo_apps_website.scheduler_enqueue_limit; the default is 10, and an invalid value or a value <= 0 falls back to 10. Module version is bumped to 18.0.1.5.9, with changelog/changelog.1.5.9.md.
Why: enqueueing 2 sources per hour could not keep up with 112+ sources on a 1-day interval. With 10 per run (hourly cron) the capacity is 240 sources per day. Above 240 sources a different approach will be needed; this MR does not try to solve that.
How verified: 19 tests of yodoo_apps_website pass; together with yodoo_apps_git_source the run is 34/34. flake8 reports 0 issues, pylint scores 10.00.
Release order: this requires yodoo_apps_git_source 18.0.1.6.0 (crnd/odoo-infrastructure MR) to be deployed first. Without it the hooks are never called and this change has no effect, with no error.
Not changed: the sync logic itself and the GitHub auth handling from the base MR.