dashboard: add windows-386-2012 builder

This change adds a Windows 386 builder with version 2012 of Windows
server. It replaces Windows 2008 as the version of Windows used for
trybot runs. It also ensures Go 1.17 is the latest version of go being
tested on Windows 2008 builders. Windows 2008 has reached its end of
life and will be phased out.

Updates golang/go#47845
Fixes golang/go#49490

Change-Id: I2307c68a74dfb41eb6a1a24177cc58835989d56b
Reviewed-on: https://go-review.googlesource.com/c/build/+/363474
Trust: Carlos Amedee <carlos@golang.org>
Run-TryBot: Carlos Amedee <carlos@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
Reviewed-by: Alexander Rakoczy <alex@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
diff --git a/dashboard/builders_test.go b/dashboard/builders_test.go
index 9bc2141..cca5e85 100644
--- a/dashboard/builders_test.go
+++ b/dashboard/builders_test.go
@@ -101,7 +101,7 @@
 				"linux-arm-aws",
 				"linux-arm64-aws",
 				"openbsd-amd64-68",
-				"windows-386-2008",
+				"windows-386-2012",
 				"windows-amd64-2016",
 
 				"misc-compile-darwinarm64",
@@ -133,7 +133,7 @@
 				"linux-arm-aws",
 				"linux-arm64-aws",
 				"openbsd-amd64-68",
-				"windows-386-2008",
+				"windows-386-2012",
 				"windows-amd64-2016",
 
 				"misc-compile-darwinarm64",
@@ -246,7 +246,7 @@
 				"netbsd-amd64-9_0",
 				"openbsd-386-68",
 				"openbsd-amd64-68",
-				"windows-386-2008",
+				"windows-386-2012",
 				"windows-amd64-2016",
 			},
 		},
@@ -256,7 +256,7 @@
 			want: []string{
 				"linux-amd64",
 				"linux-amd64-race",
-				"windows-386-2008",
+				"windows-386-2012",
 				"windows-amd64-2016",
 			},
 		},
@@ -528,7 +528,8 @@
 		{b("linux-amd64", "exp"), both},
 		{b("linux-amd64-race", "exp"), both},
 		{b("linux-amd64-longtest", "exp"), onlyPost},
-		{b("windows-386-2008", "exp"), both},
+		{b("windows-386-2008", "exp"), none},
+		{b("windows-386-2012", "exp"), both},
 		{b("windows-amd64-2016", "exp"), both},
 		{b("darwin-amd64-10_14", "exp"), onlyPost},
 		{b("darwin-amd64-10_15", "exp"), onlyPost},