Updates coordinated pipeline CI configuration
What does this MR do?
Updates coordinated pipeline CI configuration to include Slack notifications:
- Two jobs are included per environment, e.g. 
auto_deploy:notify_start:gstgandauto_deploy:notify_finish:gstg, to send a slack notification when the deployment starts or finishes - An additional stage per environment (
auto_deploy:finish:staging-canary,auto_deploy:finish:staging,auto_deploy:finish:canary) was added - For now, 
auto_deploy:finish:*stage only includes a job that sends a slack notification about the deployment status (finishedorfailed), later it can include jobs like release tracking and QA. 
Requires !1538 (merged)
Second step of gitlab-com/gl-infra/delivery#1489 (closed)
Examples
| Pipeline proof of concept | Slack message | 
|---|---|
| Screen_Recording_2021-09-15_at_16.11.25 | ![]()  | 
| Recording of a pipeline from projects created with similar configuration to release/tools and deployer | Additional examples can be found in the #deployment_notifications_tests channel (internal only) | 
Author Check-list
- [-] Has documentation been updated?
 
Edited  by Mayra Cabrera
