Revert "Enable shadow call stack by default"

This reverts commit 0b9b5e6.

args.gn

@@ -35,7 +35,6 @@ use_relative_vtables_abi = false
 # This flag was enabled as of M127, and doesn't compile as intended, contrary to upstream documentation.
 # When enabled, this increases the build time by approximately 50% without substantial benefits.
 include_both_v8_snapshots = false
-enable_shadow_call_stack = true
 
 enable_vr = false
 enable_arcore = false