Remove unnecessary html respond

* Contributes to https://gitlab.com/gitlab-org/gitlab/-/issues/351520
* Sentry error:
https://sentry.gitlab.net/gitlab/gitlabcom/issues/3237376

**Problem**

Double call of respond_to causes
ActionController::RespondToMismatchError

**Solution**

We already render 404 page for missing formats, because of that we can
remove unnecessary responder.

Changelog: changed

app/controllers/projects/refs_controller.rb

@@ -43,12 +43,7 @@ class Projects::RefsController < Projects::ApplicationController
   end
 
   def logs_tree
-    tree_summary = ::Gitlab::TreeSummary.new(
-      @commit, @project, current_user,
-      path: @path, offset: permitted_params[:offset], limit: 25)
-
     respond_to do |format|
-      format.html { render_404 }
       format.json do
         logs, next_offset = tree_summary.fetch_logs
 
@@ -61,6 +56,13 @@ class Projects::RefsController < Projects::ApplicationController
 
   private
 
+  def tree_summary
+    ::Gitlab::TreeSummary.new(
+      @commit, @project, current_user,
+      path: @path, offset: permitted_params[:offset], limit: 25
+    )
+  end
+
   def validate_ref_id
     return not_found if permitted_params[:id].present? && permitted_params[:id] !~ Gitlab::PathRegex.git_reference_regex
   end