fixes #7492 excessiveStackTrace:on shows non-absolute file in stacktrace (#8469)

lib/system.nim

@@ -3771,7 +3771,9 @@ template doAssert*(cond: bool, msg = "") =
   ## same as `assert` but is always turned on and not affected by the
   ## ``--assertions`` command line switch.
   bind instantiationInfo
-  {.line: instantiationInfo().}:
+  # NOTE: `true` is correct here; --excessiveStackTrace:on will control whether
+  # or not to output full paths.
+  {.line: instantiationInfo(-1, true).}:
     if not cond:
       raiseAssert(astToStr(cond) & ' ' &
                   instantiationInfo(-1, false).fileName & '(' &