Simnet triggers and images (#2714)

* CI: new image for simnet

* CI: chore

* CI: separate image for collator

* dockerfile: it's bad upgrading in the images

* CI: correct links to Dockerfiles

* CI: right dotenv usage

* CI: workaround GitLab's bug that failed trigger status is not reported and 'job runs forever'

* CI: debug: need instead of rules to avoid the bug

* dockerfile: fix storage

* CI: workaround sending the status when the trigger is failed

* CI: fix needed job

* CI: edit comments

* CI: trigger simnet with API

* CI: triggering script

* CI: remove real-overseer

* CI: trigger real simnet