Remove /meta_searches/tags page.

This was a search page that let you search for tags, aliases, and
implications at the same time. It never got much use and it's been
broken for a while now (the search form passed the wrong param to the
controller).

test/functional/meta_searches_controller_test.rb

@@ -1,12 +0,0 @@
-require 'test_helper'
-
-class MetaSearchesControllerTest < ActionDispatch::IntegrationTest
-  context "The meta searches controller" do
-    context "tags action" do
-      should "work" do
-        get meta_searches_tags_path, params: {name: "long_hair"}
-        assert_response :success
-      end
-    end
-  end
-end

test/unit/meta_searches/tag_test.rb

@@ -1,36 +0,0 @@
-require "test_helper"
-
-module MetaSearches
-  class TagTest < ActionMailer::TestCase
-    context "The tag metasearch" do
-      setup do
-        CurrentUser.user = FactoryBot.create(:user)
-        CurrentUser.ip_addr = "127.0.0.1"
-        FactoryBot.create(:post, :tag_string => "xxx")
-        FactoryBot.create(:tag_alias, :antecedent_name => "aaa", :consequent_name => "bbb")
-        FactoryBot.create(:tag_implication, :antecedent_name => "ccc", :consequent_name => "ddd")
-      end
-
-      should "find the tag" do
-        meta_search = MetaSearches::Tag.new(:name => "xxx")
-        meta_search.load_all
-        assert_equal(1, meta_search.tags.size)
-        assert_equal("xxx", meta_search.tags.first.name)
-      end
-
-      should "find the alias" do
-        meta_search = MetaSearches::Tag.new(:name => "aaa")
-        meta_search.load_all
-        assert_equal(1, meta_search.tag_aliases.size)
-        assert_equal("aaa", meta_search.tag_aliases.first.antecedent_name)
-      end
-
-      should "find the implication" do
-        meta_search = MetaSearches::Tag.new(:name => "ccc")
-        meta_search.load_all
-        assert_equal(1, meta_search.tag_implications.size)
-        assert_equal("ccc", meta_search.tag_implications.first.antecedent_name)
-      end
-    end
-  end
-end