refactor: replace golang.org/x/exp/slices with slices (#16772)

The experimental functions in `golang.org/x/exp/slices` are now
available in the standard library since Go 1.21.

Reference: https://go.dev/doc/go1.21#slices

Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>

coderd/healthcheck/database.go

@@ -2,10 +2,9 @@ package healthcheck
 
 import (
 	"context"
+	"slices"
 	"time"
 
-	"golang.org/x/exp/slices"
-
 	"github.com/coder/coder/v2/coderd/database"
 	"github.com/coder/coder/v2/coderd/healthcheck/health"
 	"github.com/coder/coder/v2/codersdk/healthsdk"

coderd/healthcheck/derphealth/derp.go

@@ -6,12 +6,12 @@ import (
 	"net"
 	"net/netip"
 	"net/url"
+	"slices"
 	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
 
-	"golang.org/x/exp/slices"
 	"golang.org/x/xerrors"
 	"tailscale.com/derp"
 	"tailscale.com/derp/derphttp"