ActiveRecord::QueryCanceled due to statement timeout when deleting iteration cadence
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Sentry Issue: [GITLABCOM-8FKE](https://new-sentry.gitlab.net/organizations/gitlab/issues/1570009/?referrer=gitlab_integration)
```
PG::QueryCanceled: ERROR: canceling statement due to statement timeout (PG::QueryCanceled)
CONTEXT: SQL statement "UPDATE ONLY "public"."issues" SET "sprint_id" = NULL WHERE $1 OPERATOR(pg_catalog.=) "sprint_id""
lib/gitlab/database/load_balancing/connection_proxy.rb:127:in `public_send'
connection.public_send(...)
lib/gitlab/database/load_balancing/connection_proxy.rb:127:in `block in write_using_load_balancer'
connection.public_send(...)
lib/gitlab/database/load_balancing/load_balancer.rb:145:in `block in read_write'
yield connection
lib/gitlab/database/load_balancing/load_balancer.rb:239:in `retry_with_backoff'
return yield attempt # Yield the current attempt count
lib/gitlab/database/load_balancing/load_balancer.rb:135:in `read_write'
retry_with_backoff(attempts: attempts) do |attempt|
...
(245 additional frame(s) were not displayed)
ActiveRecord::QueryCanceled: PG::QueryCanceled: ERROR: canceling statement due to statement timeout (ActiveRecord::QueryCanceled)
CONTEXT: SQL statement "UPDATE ONLY "public"."issues" SET "sprint_id" = NULL WHERE $1 OPERATOR(pg_catalog.=) "sprint_id""
```
issue