Remove the CloudSQL transactions SLO

Pierre Guinoiseaurequested to merge
pguinoiseau/drop-cloud-sql-transactions-slo into master

Remove the CloudSQL transactions SLO for Grafana and the generic Cloud SQL service, because the low traffic causes false alerts distracting EOCs, but keep it for Praefect where the traffic is high enough for the alert to be relevant.

The services still keep alerts for CPU, memory, and disk saturation (through the cloud-sql tag).

See discussion here: gitlab-com/gl-infra/production#6639 (comment 885721507)

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