Delete a problematic test case

Summary: This test case is currently failing with various different versions of `puppet-lint`. I was considering fixing this test case, but I feel that we have more than enough test cases for `ArcanistPuppetLintLinter` anyway. Since this is an `ArcanistExternalLinter`, we only really need to test that the bindings are working as expected (rather than the linter functionality).

Test Plan: `arc unit`

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D11313

src/lint/linter/__tests__/puppet-lint/2sp_soft_tabs.lint-test

@@ -1,9 +0,0 @@
-exec { 'test':
-   subscribe   => File['/etc/test'],
-   refreshonly => true,
-}
-~~~~~~~~~~
-warning:1:15
-error:2:1
-warning:2:37
-error:3:1