Use aggregate metric tables for dashboards

[bendk]

Switched to using the aggregate tables that we create using bigquery-etl. These are way faster than quering the source data. One drawback is we can't get more granular than a day, but that seems okay.

Aggregate table generation code:
https://github.com/mozilla/bigquery-etl/tree/main/sql_generators/rust_component_metrics

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[skhamis]

excited to see this coming together!