fix(frontend): remove current brain id when click on create brain (#2906)

# Description

Please include a summary of the changes and the related issue. Please
also include relevant motivation and context.

## Checklist before requesting a review

Please delete options that are not relevant.

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented hard-to-understand areas
- [ ] I have ideally added tests that prove my fix is effective or that
my feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged

## Screenshots (if appropriate):

frontend/lib/components/AddBrainModal/AddBrainModal.tsx

@@ -5,6 +5,7 @@ import { useTranslation } from "react-i18next";
 import { useFromConnectionsContext } from "@/app/chat/[chatId]/components/ActionsBar/components/KnowledgeToFeed/components/FromConnections/FromConnectionsProvider/hooks/useFromConnectionContext";
 import { Modal } from "@/lib/components/ui/Modal/Modal";
 import { addBrainDefaultValues } from "@/lib/config/defaultBrainConfig";
+import { useBrainContext } from "@/lib/context/BrainProvider/hooks/useBrainContext";
 import { useKnowledgeToFeedContext } from "@/lib/context/KnowledgeToFeedProvider/hooks/useKnowledgeToFeedContext";
 import { useUserData } from "@/lib/hooks/useUserData";
 
@@ -21,6 +22,7 @@ export const AddBrainModal = (): JSX.Element => {
   const { t } = useTranslation(["translation", "brain", "config"]);
   const { userIdentityData } = useUserData();
   const { currentStep, steps } = useBrainCreationSteps();
+  const { setCurrentBrainId } = useBrainContext();
   const {
     isBrainCreationModalOpened,
     setIsBrainCreationModalOpened,
@@ -48,6 +50,9 @@ export const AddBrainModal = (): JSX.Element => {
     setOpenedConnections([]);
     methods.reset(defaultValues);
     removeAllKnowledgeToFeed();
+    if (isBrainCreationModalOpened) {
+      setCurrentBrainId(null);
+    }
   }, [isBrainCreationModalOpened]);
 
   return (