chore: remove unused LEAD_REDIRECT_URL env var (#231)

## Summary

- Removes `LEAD_REDIRECT_URL` from `.env.example` and
`config/landing.php` as it was never referenced anywhere in the
codebase.

.env.example

@@ -70,7 +70,6 @@ AWS_DEFAULT_REGION=us-east-1
 AWS_BUCKET=
 AWS_USE_PATH_STYLE_ENDPOINT=false
 
-LEAD_REDIRECT_URL=https://google.es
 HIDE_AUTH_BUTTONS=false
 
 VITE_APP_NAME="${APP_NAME}"

config/landing.php

@@ -14,16 +14,4 @@ return [
 
     'hide_auth_buttons' => env('HIDE_AUTH_BUTTONS', false),
 
-    /*
-    |--------------------------------------------------------------------------
-    | Lead Redirect URL
-    |--------------------------------------------------------------------------
-    |
-    | The external URL to redirect users to after they submit their email
-    | on the landing page.
-    |
-    */
-
-    'lead_redirect_url' => env('LEAD_REDIRECT_URL', null),
-
 ];