Chore: Add deprecation warnings for Sentry (#60165)

pkg/setting/setting_sentry.go

@@ -1,5 +1,7 @@
 package setting
 
+import "github.com/go-kit/kit/log/level"
+
 type Sentry struct {
 	Enabled        bool    `json:"enabled"`
 	DSN            string  `json:"dsn"`
@@ -13,6 +15,7 @@ func (cfg *Cfg) readSentryConfig() {
 	raw := cfg.Raw.Section("log.frontend")
 	provider := raw.Key("provider").MustString("sentry")
 	if provider == "sentry" || provider != "grafana" {
+		_ = level.Warn(cfg.Logger).Log("msg", "\"sentry\" frontend logging provider is deprecated and will be removed in the next major version. Use \"grafana\" provider instead.")
 		cfg.Sentry = Sentry{
 			Enabled:        raw.Key("enabled").MustBool(true),
 			DSN:            raw.Key("sentry_dsn").String(),