Changes to Bitbucket Pipelines due to crypto mining abuse

Introduced two-step verification as a mandatory requirement for new Bitbucket Cloud users to enable Bitbucket Pipelines, mitigating crypto mining abuse. This change impacts new users' CI/CD user experience. Also detailed existing improvements such as strictly enforcing pipelines minutes quotas, automatic detection and blocking of abusive accounts, terminating in-progress pipelines of abusive accounts, and cluster isolation for trusted vs. untrusted workloads.