Enable FF "paginated_tree_graphql_query" by default

Contributes to https://gitlab.com/gitlab-org/gitlab/-/issues/337214

Changelog: added

config/feature_flags/development/paginated_tree_graphql_query.yml

@@ -5,4 +5,4 @@ rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/337214
 milestone: '14.2'
 type: development
 group: group::source code
-default_enabled: false
+default_enabled: true

doc/api/graphql/reference/index.md

@@ -13524,7 +13524,7 @@ Returns [`[String!]`](#string).
 
 ##### `Repository.paginatedTree`
 
-Paginated tree of the repository. Available only when feature flag `paginated_tree_graphql_query` is enabled. This flag is disabled by default, because the feature is experimental and is subject to change without notice.
+Paginated tree of the repository. Available only when feature flag `paginated_tree_graphql_query` is enabled. This flag is enabled by default.
 
 Returns [`TreeConnection`](#treeconnection).