cmd/dist: update tryDirs list to match make scripts

The $HOME/sdk/go1.17 and $HOME/go1.17 paths were initially added as
places to look for a bootstrap toolchain to make.{bash,bat,rc} scripts
and in cmd/dist (CL 370274). Those two go1.17 directories have since
been updated in the make scripts to go1.20.6 (CL 512275) and later on
to go1.22.6 (CL 606156), but the same list in cmd/dist was missed.

Fix the inconsistency now. But maybe cmd/dist doesn't need to maintain
this logic, if it's required to be invoked via one of the make scripts,
since they're responsible for setting GOROOT_BOOTSTRAP?

For #64751.

Change-Id: I0988005c559014791363138f2f722cc1f9a78bcf
Reviewed-on: https://go-review.googlesource.com/c/go/+/607821
Reviewed-by: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>

src/cmd/dist/buildtool.go

@@ -119,8 +119,8 @@ var ignoreSuffixes = []string{
 }
 
 var tryDirs = []string{
-	"sdk/go1.17",
-	"go1.17",
+	"sdk/go1.22.6",
+	"go1.22.6",
 }
 
 func bootstrapBuildTools() {