Disable Metric/BlockLength cop

[alexjfisher]

Metric/BlockLength is a new cop in rubocop 0.44.
rubocop/rubocop#3566

All puppet type definitions occur in blocks that are almost always
longer than 25 lines. I don't see much benefit in having the cop
enabled, and then having to disable it with control comments instead.

[alexjfisher]

As an example, puppet-archive build currently fails like this...

lib/puppet/provider/archive/wget.rb:1:1: C: Metrics/BlockLength: Block has too many lines. [32/25]
Puppet::Type.type(:archive).provide(:wget, parent: :ruby) do ...
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
lib/puppet/provider/archive/curl.rb:1:1: C: Metrics/BlockLength: Block has too many lines. [34/25]
Puppet::Type.type(:archive).provide(:curl, parent: :ruby) do ...
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
lib/puppet/provider/archive/ruby.rb:15:1: C: Metrics/BlockLength: Block has too many lines. [140/25]
Puppet::Type.type(:archive).provide(:ruby) do ...
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
lib/puppet/type/archive.rb:6:1: C: Metrics/BlockLength: Block has too many lines. [214/25]
Puppet::Type.newtype(:archive) do ...
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
lib/puppet/type/archive.rb:9:3: C: Metrics/BlockLength: Block has too many lines. [33/25]
  ensurable do ...
  ^^^^^^^^^^^^