Enable unparam, prealloc, sqlclosecheck linters

.golangci.yml

connector/atlassiancrowd/atlassiancrowd.go

connector/atlassiancrowd/atlassiancrowd_test.go

connector/bitbucketcloud/bitbucketcloud.go

connector/gitea/gitea.go

connector/ldap/ldap.go

connector/saml/saml.go

server/api.go

server/deviceflowhandlers.go

server/server.go

storage/conformance/conformance.go

storage/etcd/etcd.go

storage/kubernetes/k8sapi/client.go

storage/sql/crud.go

storage/storage.go