Remove workaround from the "must convert input to uppercase" scripting integration test

It's no longer necessary after commit 1c73e52 that caused the document
to be closed properly between tests, and this therefore partly reverts
commit 973b67f.

test/integration/scripting_spec.mjs

@@ -1197,13 +1197,6 @@ describe("Interaction", () => {
           await page.waitForFunction(
             `${getQuerySelector("27R")}.value === "HEAO "`
           );
-
-          // The typing actions in the first textbox caused sandbox events to be
-          // queued. We don't close the document between tests, so we have to
-          // flush them here, by clicking the second textbox, so they don't leak
-          // through to the following test.
-          await page.click(getSelector("28R"));
-          await waitForSandboxTrip(page);
         })
       );
     });