Bug 41036: Remove go_vendor-lyrebird-nightly makefile target

Since after #40948 we don't check lyrebird-vendor sha256sum in nightly,
we don't need to use the `go_vendor-lyrebird-nightly` makefile target
anymore.

Makefile

@@ -643,9 +643,6 @@ go_vendor-webtunnel-alpha: submodule-update
 go_vendor-lyrebird-alpha: submodule-update
 	$(rbm) build lyrebird --step go_vendor --target alpha --target torbrowser-linux-x86_64
 
-go_vendor-lyrebird-nightly: submodule-update
-	$(rbm) build lyrebird --step go_vendor --target nightly --target torbrowser-linux-x86_64
-
 
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 # rcodesign #