hostinfo, net/netcheck: use CutPrefix

Updates #5309

Change-Id: I37e594cfd245784bf810c493de68a66d3ff20677
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

cmd/derper/depaware.txt

@@ -69,6 +69,7 @@ tailscale.com/cmd/derper dependencies: (generated by github.com/tailscale/depawa
    W    tailscale.com/util/endian                                    from tailscale.com/net/netns
         tailscale.com/util/lineread                                  from tailscale.com/hostinfo+
         tailscale.com/util/singleflight                              from tailscale.com/net/dnscache
+   L    tailscale.com/util/strs                                      from tailscale.com/hostinfo
    W 💣 tailscale.com/util/winutil                                   from tailscale.com/hostinfo+
         tailscale.com/version                                        from tailscale.com/derp+
         tailscale.com/version/distro                                 from tailscale.com/hostinfo+

cmd/tailscale/depaware.txt

@@ -95,6 +95,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         tailscale.com/util/lineread                                  from tailscale.com/net/interfaces+
         tailscale.com/util/mak                                       from tailscale.com/net/netcheck
         tailscale.com/util/singleflight                              from tailscale.com/net/dnscache
+   L    tailscale.com/util/strs                                      from tailscale.com/hostinfo
    W 💣 tailscale.com/util/winutil                                   from tailscale.com/hostinfo+
         tailscale.com/version                                        from tailscale.com/cmd/tailscale/cli+
         tailscale.com/version/distro                                 from tailscale.com/cmd/tailscale/cli+

cmd/tailscaled/depaware.txt

@@ -280,6 +280,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/util/pidowner                                  from tailscale.com/ipn/ipnserver
         tailscale.com/util/racebuild                                 from tailscale.com/logpolicy
         tailscale.com/util/singleflight                              from tailscale.com/control/controlclient+
+   L    tailscale.com/util/strs                                      from tailscale.com/hostinfo
         tailscale.com/util/systemd                                   from tailscale.com/control/controlclient+
         tailscale.com/util/uniq                                      from tailscale.com/wgengine/magicsock
      💣 tailscale.com/util/winutil                                   from tailscale.com/cmd/tailscaled+

hostinfo/hostinfo_linux.go

@@ -16,6 +16,7 @@ import (
 
 	"golang.org/x/sys/unix"
 	"tailscale.com/util/lineread"
+	"tailscale.com/util/strs"
 	"tailscale.com/version/distro"
 )
 
@@ -50,7 +51,7 @@ func linuxDeviceModel() string {
 
 func getQnapQtsVersion(versionInfo string) string {
 	for _, field := range strings.Fields(versionInfo) {
-		if suffix := strings.TrimPrefix(field, "QTSFW_"); suffix != field {
+		if suffix, ok := strs.CutPrefix(field, "QTSFW_"); ok {
 			return "QTS " + suffix
 		}
 	}

net/netcheck/netcheck_test.go

@@ -21,6 +21,7 @@ import (
 	"tailscale.com/net/stun"
 	"tailscale.com/net/stun/stuntest"
 	"tailscale.com/tailcfg"
+	"tailscale.com/util/strs"
 )
 
 func TestHairpinSTUN(t *testing.T) {
@@ -616,7 +617,7 @@ func TestLogConciseReport(t *testing.T) {
 			var buf bytes.Buffer
 			c := &Client{Logf: func(f string, a ...any) { fmt.Fprintf(&buf, f, a...) }}
 			c.logConciseReport(tt.r, dm)
-			if got := strings.TrimPrefix(buf.String(), "[v1] report: "); got != tt.want {
+			if got, ok := strs.CutPrefix(buf.String(), "[v1] report: "); !ok {
 				t.Errorf("unexpected result.\n got: %#q\nwant: %#q\n", got, tt.want)
 			}
 		})