Use blocking tests and sunset reliable test bucket

What does this MR do and why?

To achieve KR 2: Optimize end-to-end testing in auto deployments to achieve a 25% reduction in both testing duration and blockages caused by unreliable tests, we are bringing with this MR:

• Promoting tests to from reliable to smoke to increase smoke coverage
• Promote from blocking to smoke with the same rationale as ☝
• Use only :blocking, instead of :reliable and adjust the Blocking scenario tags
• Since there is a significant amount of blocking, the parallelization was increased

Follow-up

• Remove reliable jobs in dotcom
• Remove reliable-related code

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.