Don't use a 1d interval for timeseries for SLA

This changes the interval for the timeseries graphs on the General SLA dashboard.

This changes the graphs from a single point per day, to dynamic timeseries graphs. This allows us to see more precisely what influenced the availability number rather than just the day it happened.

Example showing a maintenance window:

• Before: https://dashboards.gitlab.net/d/general-slas/general-slas?orgId=1&from=1662189300000&to=1662320339000
• After: https://dashboards.gitlab.net/dashboard/snapshot/P403U6KzR1dPcUtJCr0aL598DaVd5dLM?orgId=1&from=1662189300000&to=1662320339000