fix(api): Fix metrics lifecycle policies tasks

[hayk96]

1. What this PR does / why we need it:

• [ENHANCEMENT] Added a new endpoint: [POST] /metrics-lifecycle-policies/trigger for force-triggering all Metrics Lifecycle Policies.
• [CHANGE] Changed the execution interval of the task "Clean-up Prometheus series" by the scheduler to 2 hours (previously 20 minutes).
• [BUGFIX] Prevented the execution of more than one task at the same time, as tasks can remain in the running state for longer than their execution interval.

2. Make sure that you've checked the boxes below before you submit PR:

• DCO signed
• No conflict with the main branch.