Add deprecation message on Firebird / Sqlserver / Oracle database tasks.

activerecord/lib/active_record/tasks/firebird_database_tasks.rb

@@ -4,6 +4,7 @@ class FirebirdDatabaseTasks # :nodoc:
       delegate :connection, :establish_connection, to: ActiveRecord::Base
 
       def initialize(configuration)
+        ActiveSupport::Deprecation.warn "This database tasks were deprecated, because this tasks should be served by the 3rd party adapter."
         @configuration = configuration
       end
 

activerecord/lib/active_record/tasks/oracle_database_tasks.rb

@@ -4,6 +4,7 @@ class OracleDatabaseTasks # :nodoc:
       delegate :connection, :establish_connection, to: ActiveRecord::Base
 
       def initialize(configuration)
+        ActiveSupport::Deprecation.warn "This database tasks were deprecated, because this tasks should be served by the 3rd party adapter."
         @configuration = configuration
       end
 

activerecord/lib/active_record/tasks/sqlserver_database_tasks.rb

@@ -6,6 +6,7 @@ class SqlserverDatabaseTasks # :nodoc:
       delegate :connection, :establish_connection, to: ActiveRecord::Base
 
       def initialize(configuration)
+        ActiveSupport::Deprecation.warn "This database tasks were deprecated, because this tasks should be served by the 3rd party adapter."
         @configuration = configuration
       end