chore: Send applicationDetail in create application payload (appsmi…

…thorg#28272)

## Description
- Add the `applicationDetail` payload to the create application request.
- This allows instances which have Anvil enabled, to default to Anvil
when an application is created.

#### PR fixes following issue(s)
Fixes appsmithorg#28237 

#### Type of change
- Chore (housekeeping or task changes that don't impact user perception)

#### How Has This Been Tested?
- [x] Manual
- [ ] JUnit
- [ ] Jest
- [ ] Cypress - If all existing tests pass, we're good to merge

## Checklist:
#### Dev activity
- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my own code
- [ ] I have commented my code, particularly in hard-to-understand areas
- [ ] I have made corresponding changes to the documentation
- [ ] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] PR is being merged under a feature flag


#### QA activity:
- [ ] [Speedbreak
features](https://github.com/appsmithorg/TestSmith/wiki/Guidelines-for-test-plans#speedbreakers-)
have been covered
- [ ] Test plan covers all impacted features and [areas of
interest](https://github.com/appsmithorg/TestSmith/wiki/Guidelines-for-test-plans#areas-of-interest-)
- [ ] Test plan has been peer reviewed by project stakeholders and other
QA members
- [ ] Manually tested functionality on DP
- [ ] We had an implementation alignment call with stakeholders post QA
Round 2
- [ ] Cypress test cases have been added and approved by SDET/manual QA
- [ ] Added `Test Plan Approved` label after Cypress tests were reviewed
- [ ] Added `Test Plan Approved` label after JUnit tests were reviewed

---------

Co-authored-by: nilansh <[email protected]>

app/client/src/ce/api/ApplicationApi.tsx

@@ -307,6 +307,11 @@ export class ApplicationApi extends Api {
         name: request.name,
         color: request.color,
         icon: request.icon,
+        applicationDetail: {
+          appPositioning: {
+            type: request.layoutSystemType,
+          },
+        },
       },
     );
   }

app/client/src/selectors/layoutSystemSelectors.ts

@@ -5,10 +5,6 @@ import { LayoutSystemTypes } from "layoutSystems/types";
  * selector to fetch the application's layout type
  */
 export const getLayoutSystemType = (state: AppState) => {
-  const featureFlag = state.ui.users.featureFlag.data;
-  if (featureFlag && featureFlag.release_anvil_enabled === true) {
-    return LayoutSystemTypes.ANVIL;
-  }
   if (
     state.ui.applications?.currentApplication?.applicationDetail?.appPositioning
       ?.type