Optimize metadata queries (#7013)

In this PR:

1. Refactor guards to avoid duplicated queries: WorkspaceAuthGuard and
UserAuthGuard only check for existence of workspace and user in the
request without querying the database

packages/twenty-server/src/engine/metadata-modules/utils/validate-field-name-availability.utils.ts

@@ -32,6 +32,10 @@ export const validateFieldNameAvailabilityOrThrow = (
   const reservedCompositeFieldsNames =
     getReservedCompositeFieldNames(objectMetadata);
 
+  if (objectMetadata.fields.some((field) => field.name === name)) {
+    throw new NameNotAvailableException(name);
+  }
+
   if (reservedCompositeFieldsNames.includes(name)) {
     throw new NameNotAvailableException(name);
   }