Refactor usage of legacy data contracts. Moves legacy data contracts
to pkg/tsdb/legacydata package.
Refactor pkg/expr to be a proper service/dependency that can be provided
to wire to remove some unneeded dependencies to SSE in ngalert and other places.
Refactor pkg/expr to not use the legacydata,RequestHandler and use
backend.QueryDataHandler instead.
This commit fixes an issue in alerting where NoDataFound is false
when using the AND operator to compare two conditions in an alert
rule and one of the conditions has no data.
* Metrics: remove unused metrics
Metric `M_Grafana_Version` is not used anywhere, nor the mentioned
`M_Grafana_Build_Version`. Seems to be an artefact?
* Metrics: make the naming consistent
* Metrics: add comments to exported vars
* Metrics: use proper naming
Fixes#18110
* tech(routines): move the async logic from notification to alerting notifier
* tech(notification): reduce code dupe
* fix(notification): dont touch the response unless its an error
* feat(alerting): make alerting exeuction async but flow sync
* tech(alerting): remove commented code
* tech(alerting): remove unused code
* tech(alerting): fix typo
* tech(alerting): implement Context on EvalContext
* tech(alerting): wait for all alerts to return
* feat(alerting): dont allow alert responses to cancel
* Revert "feat(alerting): dont allow alert responses to cancel"
This reverts commit 324b006c96.
* feat(alerting): give alerts some time to finish before closing down
