[breaking-change] Remove the `log-level` config option.

This reverts commit 351d0a0c85a946d5a453b36ffbc5fe8a64f52a5f.

This option does not have any effect at the moment and may potentially
confuse users. It can be easily reintroduced later (by reverting this
commit) once we start logging at any level other than `info`.

conf/config.example.toml

···
 # as the intrinsic default value.
 
 log-format = "text"
-log-level = "info"
 
 [server]
 # Use "-" to disable the handler.

src/config.go

···
 	Insecure      bool                `toml:"-" env:"insecure"`
 	Features      []string            `toml:"features"`
 	LogFormat     string              `toml:"log-format" default:"text"`
-	LogLevel      string              `toml:"log-level" default:"info"`
 	Server        ServerConfig        `toml:"server"`
 	Wildcard      []WildcardConfig    `toml:"wildcard"`
 	Fallback      FallbackConfig      `toml:"fallback"`

src/observe.go

···
 	"os"
 	"runtime/debug"
 	"strconv"
-	"strings"
 	"sync"
 	"time"
 
···
 
 	logHandlers := []slog.Handler{}
 
-	logLevel := slog.LevelInfo
-	switch strings.ToLower(config.LogLevel) {
-	case "debug":
-		logLevel = slog.LevelDebug
-	case "info":
-		logLevel = slog.LevelInfo
-	case "warn":
-		logLevel = slog.LevelWarn
-	case "error":
-		logLevel = slog.LevelError
-	default:
-		log.Println("unknown log level", config.LogLevel)
-	}
-
 	switch config.LogFormat {
 	case "none":
 		// nothing to do
 	case "text":
 		logHandlers = append(logHandlers,
-			slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: logLevel}))
+			slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{}))
 	case "json":
 		logHandlers = append(logHandlers,
-			slog.NewJSONHandler(os.Stderr, &slog.HandlerOptions{Level: logLevel}))
+			slog.NewJSONHandler(os.Stderr, &slog.HandlerOptions{}))
 	default:
 		log.Println("unknown log format", config.LogFormat)
 	}
···
 		var err error
 		syslogHandler, err = syslog.NewHandler(&syslog.HandlerOptions{
 			Address:          syslogAddr,
-			Level:            logLevel,
 			AppName:          "git-pages",
 			StructuredDataID: "git-pages",
 		})
···
 		if enableLogs {
 			logHandlers = append(logHandlers, sentryslog.Option{
 				AddSource: true,
-				LogLevel:  levelsFromMinimum(logLevel),
 			}.NewSentryHandler(context.Background()))
 		}
 	}
 
 	slog.SetDefault(slog.New(slogmulti.Fanout(logHandlers...)))
-}
-
-// From sentryslog, because for some reason they don't make it public.
-func levelsFromMinimum(minLevel slog.Level) []slog.Level {
-	allLevels := []slog.Level{slog.LevelDebug, slog.LevelInfo, slog.LevelWarn, slog.LevelError, sentryslog.LevelFatal}
-	var result []slog.Level
-	for _, level := range allLevels {
-		if level >= minLevel {
-			result = append(result, level)
-		}
-	}
-	return result
 }
 
 func FiniObservability() {