Allow hiding new formula/cask sections on update

Library/Homebrew/cmd/update-report.rb

@@ -749,8 +749,10 @@ class ReporterHub
       report_all = false
     end
 
+    unless Homebrew::EnvConfig.no_update_report_new?
       dump_new_formula_report
       dump_new_cask_report
+    end
     dump_renamed_formula_report if report_all
     dump_renamed_cask_report if report_all
     dump_deleted_formula_report(report_all)

Library/Homebrew/env_config.rb

@@ -327,6 +327,10 @@ module Homebrew
                      "from running `brew install` <formula> or `brew upgrade` <formula>.",
         boolean:     true,
       },
+      HOMEBREW_NO_UPDATE_REPORT_NEW:             {
+        description: "If set, `brew update` will not show the list of newly added formulae/casks.",
+        boolean:     true,
+      },
       HOMEBREW_PIP_INDEX_URL:                    {
         description:  "If set, `brew install <formula>` will use this URL to download PyPI package resources.",
         default_text: "`https://pypi.org/simple`.",

Library/Homebrew/env_config.rbi

@@ -190,6 +190,9 @@ module Homebrew::EnvConfig
   sig { returns(T::Boolean) }
   def self.no_installed_dependents_check?; end
 
+  sig { returns(T::Boolean) }
+  def self.no_update_report_new?; end
+
   sig { returns(T.nilable(String)) }
   def self.no_proxy; end