testing: enable 'newstore' feature by default

Enable 'newstore' by default for testing.

Signed-off-by: Wei Zhang <weizhang555.zw@gmail.com>

Makefile

@@ -165,7 +165,7 @@ DEFMEMSLOTS := 10
 DEFBRIDGES := 1
 DEFDISABLEGUESTSECCOMP := true
 #Default experimental features enabled
-DEFAULTEXPFEATURES := []
+DEFAULTEXPFEATURES := ['newstore']
 
 #Default entropy source
 DEFENTROPYSOURCE := /dev/urandom