Revert "add era units in Thai"

This reverts commit 4550d25a4d89f9600fc3be8542d7e05fd653c795.

cmd/resources/data/rules/th.yaml

@@ -74,10 +74,6 @@ datetime:
       medium: '{1}, {0}'
       short: '{1}, {0}'
   formatNames:
-    eras:
-      abbreviated:
-        ad: "\u0E04.\u0E28."
-        be: "\u0E1E.\u0E28."
     months:
       abbreviated:
         "1": "\u0E21.\u0E04."