analytics: tweak behaviour.

- Use separate method for `not_this_run?` so we can still set the
  analytics message as seen when set.
- Clarify when analytics message is printed that we haven't sent any
  analytics yet.

Library/Homebrew/cmd/update-report.rb

@@ -51,6 +51,7 @@ module Homebrew
       puts <<~EOS
         #{Tty.bold}Read the analytics documentation (and how to opt-out) here:
           #{Formatter.url("https://docs.brew.sh/Analytics")}#{Tty.reset}
+        No analytics have been recorded yet (or will be during this `brew` run).
 
       EOS
 

Library/Homebrew/utils/analytics.rb

@@ -6,6 +6,7 @@ module Utils
   module Analytics
     class << self
       def report(type, metadata = {})
+        return if not_this_run?
         return if disabled?
 
         args = []
@@ -77,11 +78,15 @@ module Utils
       end
 
       def disabled?
-        return true if ENV["HOMEBREW_NO_ANALYTICS"] || ENV["HOMEBREW_NO_ANALYTICS_THIS_RUN"]
+        return true if ENV["HOMEBREW_NO_ANALYTICS"]
 
         config_true?(:analyticsdisabled)
       end
 
+      def not_this_run?
+        ENV["HOMEBREW_NO_ANALYTICS_THIS_RUN"].present?
+      end
+
       def no_message_output?
         # Used by Homebrew/install
         ENV["HOMEBREW_NO_ANALYTICS_MESSAGE_OUTPUT"].present?