LibJS+Everywhere: Remove all VM::clear_exception() calls

Since VM::exception() no longer exists this is now useless. All of these
calls to clear_exception were just to clear the VM state after some
(potentially) failed evaluation and did not use the exception itself.

Userland/Libraries/LibJS/Runtime/Promise.cpp

@@ -114,7 +114,6 @@ Promise::ResolvingFunctions Promise::create_resolving_functions()
         if (then.is_throw_completion()) {
             // a. Return RejectPromise(promise, then.[[Value]]).
             dbgln_if(PROMISE_DEBUG, "[Promise @ {} / PromiseResolvingFunction]: Exception while getting 'then' property, rejecting with error", &promise);
-            vm.clear_exception();
             return promise.reject(*then.throw_completion().value());
         }