internal/relui: switch to new signing path

Also update test data to match, since the fake signing service now
applies a signature. Check that it's a signature of the right type.

For golang/go#53632.

Change-Id: Iea2321e0e0c41ce12e2a6152a2300f03e592c546
Reviewed-on: https://go-review.googlesource.com/c/build/+/447299
Auto-Submit: Dmitri Shuralyov <[email protected]>
Reviewed-by: Carlos Amedee <[email protected]>
Run-TryBot: Dmitri Shuralyov <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>

Author: dmitshur

internal/relui/buildrelease_test.go

@@ -302,7 +302,7 @@ func testRelease(t *testing.T, wantVersion string, kind task.ReleaseKind) {
 		OS:   "windows",
 		Arch: "amd64",
 		Kind: "installer",
-	}, "I'm an MSI!\n")
+	}, "I'm an MSI!\n-signed <Windows>")
 	checkTGZ(t, dlURL, files, "linux-amd64.tar.gz", &task.WebsiteFile{
 		OS:   "linux",
 		Arch: "amd64",
@@ -332,7 +332,7 @@ func testRelease(t *testing.T, wantVersion string, kind task.ReleaseKind) {
 		OS:   "darwin",
 		Arch: "amd64",
 		Kind: "installer",
-	}, "I'm a .pkg!\n")
+	}, "I'm a PKG!\n-signed <macOS>")
 
 	head, err := deps.gerrit.ReadBranchHead(deps.ctx, "dl", "master")
 	if err != nil {

internal/relui/workflows.go

@@ -365,8 +365,8 @@ func addCommTasks(
 	wf.Output(wd, "Tweet URL", tweetURL)
 }
 
-// TODO(go.dev/issue/53632): Flip to true and later on delete.
-const useSignService = false
+// TODO(go.dev/issue/53632): Later on: delete the const and all the unused code. 🎉
+const useSignService = true
 
 func addSingleReleaseWorkflow(
 	build *BuildReleaseTasks, milestone *task.MilestoneTasks, version *task.VersionTasks,