[jk] Update Trigger SLA start condition

[johnson-mage]

Description

• Use a trigger's started_at time (instead of execution_date) for calculating when its SLA time limit has been exceeded (and trigger's passed_sla property is updated to true). Also check trigger's pipeline runs with running status, excluding runs with initial status, when calculating SLA time limit.
• Update pipeline runs table to visually indicate runs that have exceeded SLA time limit (passed_sla is true).

How Has This Been Tested?

• Updated unit tests
• Tested in both single-project and multi-project setups

Pipeline runs table with run that has exceeded SLA of 1 minute ("Execution time" has yellow font color):

These 5 pipeline runs in the screenshot below were executed at the same time for a pipeline with a pipeline_run_limit of 1 for its concurrency config (meaning only 1 pipeline run can run at a time). None of the pipeline runs exceeded the SLA time limit (previously, the pipeline runs besides the initial run were being flagged as exceeding the SLA limit even though their execution times were below it).

Checklist

• The PR is tagged with proper labels (bug, enhancement, feature, documentation)
• I have performed a self-review of my own code
• I have added unit tests that prove my fix is effective or that my feature works
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• If new documentation has been added, relative paths have been added to the appropriate section of docs/mint.json