Fix low-hanging rubocop gripes (#8458)

* rubocop: quit being so picky

* rubocop: miscellany

* rubocop: prefer present to blank

app/models/concerns/expireable.rb

@@ -9,7 +9,7 @@ module Expireable
     attr_reader :expires_in
 
     def expires_in=(interval)
-      self.expires_at = interval.to_i.seconds.from_now unless interval.blank?
+      self.expires_at = interval.to_i.seconds.from_now if interval.present?
       @expires_in     = interval
     end
 

app/models/user.rb

@@ -98,7 +98,7 @@ class User < ApplicationRecord
            :reduce_motion, :system_font_ui, :noindex, :theme, :display_sensitive_media, :hide_network,
            :default_language, to: :settings, prefix: :setting, allow_nil: false
 
-  attr_accessor :invite_code
+  attr_reader :invite_code
 
   def pam_conflict(_)
     # block pam login tries on traditional account
@@ -258,7 +258,7 @@ class User < ApplicationRecord
   end
 
   def invite_code=(code)
-    self.invite  = Invite.find_by(code: code) unless code.blank?
+    self.invite  = Invite.find_by(code: code) if code.present?
     @invite_code = code
   end