[v16] Fix spurious warning when tbot is initialised prior to teleport configure (#60257)

* Fix spurious warning when `tbot` is installed prior to `teleport
configure`

* Use slices.DeleteFunc

* Add slices package

Author: strideynet

tool/teleport/common/teleport.go

@@ -28,6 +28,7 @@ import (
 	"os/user"
 	"path"
 	"path/filepath"
+	"slices"
 	"strconv"
 	"strings"
 
@@ -906,6 +907,12 @@ func onConfigDump(flags dumpFlags) error {
 			os.Stderr, "%s Could not check the contents of %s: %s\n         The data directory may contain existing cluster state.\n", utils.Color(utils.Yellow, "WARNING:"), flags.DataDir, err.Error())
 	}
 
+	// Filter out the default directory /var/lib/teleport/bot used by `tbot` to
+	// avoid throwing a scary warning if `tbot` was installed prior to
+	// configuring teleport.
+	entries = slices.DeleteFunc(entries, func(entry os.DirEntry) bool {
+		return entry.Name() == "bot"
+	})
 	if err == nil && len(entries) != 0 {
 		fmt.Fprintf(
 			os.Stderr,