Remove obsolete Logger severity predicates

The Logger severity predicates have existed since the [introduction of
Logger][1]. However, these methods only looked at the `level` instance
variable, so they did not work with the [thread safe implementation][2]
of temporary log levels in Rails.

Since then, the Logger severity predicates were [updated][3] to use the
`level` method instead of the instance variable, making Rails' severity
predicate overrides obsolete.

This commit removes Rails' custom severity predicates in favor of
Logger's implementation, since the new implementation was released in
Logger 1.4.2 and came bundled with Ruby 2.7.0.

[1]: ruby/logger@525b58d
[2]: rails/rails@629efb6
[3]: ruby/logger@7365c99

Gemfile.lock

@@ -93,7 +93,7 @@ PATH
       connection_pool (>= 2.2.5)
       drb
       i18n (>= 1.6, < 2)
-      logger
+      logger (>= 1.4.2)
       minitest (>= 5.1)
       tzinfo (~> 2.0, >= 2.0.5)
     rails (8.0.0.alpha)

activesupport/activesupport.gemspec

@@ -42,5 +42,5 @@ Gem::Specification.new do |s|
   s.add_dependency "base64"
   s.add_dependency "drb"
   s.add_dependency "bigdecimal"
-  s.add_dependency "logger"
+  s.add_dependency "logger",          ">= 1.4.2"
 end

activesupport/lib/active_support/logger_thread_safe_level.rb

@@ -7,14 +7,6 @@ module ActiveSupport
   module LoggerThreadSafeLevel # :nodoc:
     extend ActiveSupport::Concern
 
-    Logger::Severity.constants.each do |severity|
-      class_eval(<<-EOT, __FILE__, __LINE__ + 1)
-        def #{severity.downcase}?                # def debug?
-          Logger::#{severity} >= level           #   DEBUG >= level
-        end                                      # end
-      EOT
-    end
-
     def local_level
       IsolatedExecutionState[local_level_key]
     end

activesupport/test/broadcast_logger_test.rb

@@ -369,6 +369,26 @@ def add(message_level, message = nil, progname = nil, &block)
         @adds << [message_level, message, progname] if message_level >= local_level
       end
 
+      def debug?
+        level <= ::Logger::DEBUG
+      end
+
+      def info?
+        level <= ::Logger::INFO
+      end
+
+      def warn?
+        level <= ::Logger::WARN
+      end
+
+      def error?
+        level <= ::Logger::ERROR
+      end
+
+      def fatal?
+        level <= ::Logger::FATAL
+      end
+
       def close
         @closed = true
       end