remove declaration of max_uint48 with is not available by default in CVL2

certora/specs/helpers/helpers.spec

@@ -2,9 +2,6 @@
 definition nonpayable(env e) returns bool = e.msg.value == 0;
 definition nonzerosender(env e) returns bool = e.msg.sender != 0;
 
-// constants
-// definition max_uint48() returns mathint = (1 << 48) - 1;
-
 // math
 definition min(mathint a, mathint b) returns mathint = a < b ? a : b;
 definition max(mathint a, mathint b) returns mathint = a > b ? a : b;