(maint) Remove unnecessary Puppet.settings.clear calls from specs

I believe most of these predated our clearing the settings before each
test in the central puppet/test/test_helper.rb. And since we then set
some base settings (such as :environment_timeout) in the test_helper,
the effect of a secondary clear in the test itself is to wipe out the
baseline setup test_helper just laid down.

In particular this is a problem with environment_timeout, as it leads to
tests which end up creating environments, getting them cached with the
default 180s timeout, which can leak to subsequent tests and create
unpleasant spec order issues.
(doc) Note how to obtain spec_order from parallel-spec runs

Courtesy of Peter Huene.
Merge pull request #2909 from jpartlow/maint/master/remove-extra-settings-clear-from-specs

Maint/master/remove extra settings clear from specs