Github Actions: Remove --disable-tests

With --disable-tests, for example for Go the `make check` under `lib/go`
would only run unit tests under `lib/go/thrift` but not the unit tests
under `lib/go/test`.

Also some changes in lib/go/test/fuzz/Makefile.am so it works in both go
1.20 and 1.21 (The current state breaks in 1.21 but because of
`--disable-tests` we never noticed that).
diff --git a/lib/go/test/fuzz/fuzz.go b/lib/go/test/fuzz/fuzz.go
index cd99d58d..0698379 100644
--- a/lib/go/test/fuzz/fuzz.go
+++ b/lib/go/test/fuzz/fuzz.go
@@ -1,3 +1,4 @@
+//go:build gofuzz
 // +build gofuzz
 
 /*
@@ -26,9 +27,8 @@
 	"fmt"
 	"strconv"
 
-	"shared"
-	"tutorial"
-
+	"github.com/apache/thrift/lib/go/test/fuzz/gen-go/shared"
+	"github.com/apache/thrift/lib/go/test/fuzz/gen-go/tutorial"
 	"github.com/apache/thrift/lib/go/thrift"
 )