fix(settings): Clear error messages on submit SigninTokenCode/ConfirmSignupCode

Because:

* Error banners were not cleared on submit even if error no longer applied (e.g., throttling) and could result in both an (outdated) error banner and an error tooltip being displayed simultaneously

This commit:

* clear error messages on submit for both SigninTokenCode and ConfirmSignupCode pages

Closes #FXA-11059

Author: vpomerleau

packages/fxa-settings/src/pages/Signin/SigninTokenCode/index.tsx

@@ -119,8 +119,14 @@ const SigninTokenCode = ({
     }
   };
 
+  const clearErrorMessages = () => {
+    setLocalizedErrorBannerMessage('');
+    setCodeErrorMessage('');
+  };
+
   const onSubmit = useCallback(
     async (code: string) => {
+      clearErrorMessages();
       if (!SIX_DIGIT_NUMBER_REGEX.test(code)) {
         setCodeErrorMessage(localizedInvalidCode);
         return;

packages/fxa-settings/src/pages/Signup/ConfirmSignupCode/index.tsx

@@ -114,7 +114,13 @@ const ConfirmSignupCode = ({
     }
   }
 
+  function clearErrorMessages() {
+    setLocalizedErrorBannerHeading('');
+    setCodeErrorMessage('');
+  }
+
   async function verifySession(code: string) {
+    clearErrorMessages();
     logViewEvent(`flow.${viewName}`, 'submit', REACT_ENTRYPOINT);
     GleanMetrics.signupConfirmation.submit();
     try {