Remove the Tailwind Dangerfile

This Dangerfile used to report CSS utils that were built using string
interpolation. Since introducing it, we have created an ESLint and a
Rubocop rules to perform the same checks, thus providing a better
developer experience for spotting this offences.

The Dangerfile can therefore be removed.

danger/tailwindcss/Dangerfile

-# frozen_string_literal: true
-
-module Danger
-  class Tailwind
-    FRONTEND_INTERPOLATION_PATTERN = /gl-[0-9a-z-]+(\$\{|['"] ?\+)/
-    BACKEND_INTERPOLATION_PATTERN = /gl-[0-9a-z-]+(#\{|['"] ?\+)/
-
-    def initialize(helper, git)
-      @helper = helper
-      @git = git
-    end
-
-    def report_interpolated_utils
-      frontend_files_with_interpolated_utils = files_with_interpolated_utils(
-        frontend_tailwindy_files(@helper.all_changed_files), FRONTEND_INTERPOLATION_PATTERN)
-      backend_files_with_interpolated_utils = files_with_interpolated_utils(
-        backend_tailwindy_files(@helper.all_changed_files), BACKEND_INTERPOLATION_PATTERN)
-
-      return "" if frontend_files_with_interpolated_utils.empty? && backend_files_with_interpolated_utils.empty?
-
-      <<~MARKDOWN
-      ### Interpolated utils
-
-      The following files might contain interpolated utils:
-      #{format_files_list(frontend_files_with_interpolated_utils + backend_files_with_interpolated_utils)}
-
-      If you are leveraging CSS utilities, make sure they are written in full and not built via string
-      interpolation as that would prevent Tailwind CSS from generating them.
-      MARKDOWN
-    end
-
-    private
-
-    def frontend_tailwindy_files(files)
-      files.select do |file|
-        file.end_with?('.vue', '.js')
-      end
-    end
-
-    def backend_tailwindy_files(files)
-      files.select do |file|
-        file.end_with?('.html.haml', '.rb')
-      end
-    end
-
-    def files_with_interpolated_utils(files, pattern)
-      files.select do |file|
-        diff = @git.diff_for_file(file)
-
-        # When a file is just moved around it appears in the changed files list
-        # but the diff is empty so we are skipping it.
-        next if diff.nil?
-
-        diff.patch.each_line.any? do |line|
-          line.start_with?('+') && line.match?(pattern)
-        end
-      end
-    end
-
-    def format_files_list(files)
-      files.map do |file|
-        "- `#{file}`"
-      end.join("\n")
-    end
-  end
-end
-
-danger_tailwind = Danger::Tailwind.new(helper, git)
-report = danger_tailwind.report_interpolated_utils
-
-unless report.empty?
-  markdown <<~MSG
-   ## Tailwind CSS
-
-   #{report}
-  MSG
-end