Revert "DEV: enables threadsafe for system tests"

This reverts commit b8100ad1ae.

This was causing many issues in CI, including AR connections
not being expired because of threading issues, which was also
causing rails_helper to raise an error because we had busy
connections at the end of spec runs.

```
Cannot expire connection, it is owned by a different thread:
/__w/discourse/discourse/vendor/bundle/ruby/3.1.0/gems/puma-6.0.1/lib/puma/thread_pool.rb:106
sleep_forever>. Current thread: #<Thread:0x00007f541966fcc8 run>.
```

And:

```
Failure/Error: raise ActiveRecord::Base.connection_pool.stat.inspect

RuntimeError:
  {:size=>5, :connections=>2, :busy=>2, :dead=>0, :idle=>0, :waiting=>0, :checkout_timeout=>5.0}
```

See https://github.com/discourse/discourse/actions/runs/3825882529/jobs/6509204143
for examples.

plugins/chat/spec/system/chat_channel_spec.rb

@@ -24,7 +24,8 @@ RSpec.describe "Chat channel", type: :system, js: true do
       expect(channel).to have_no_loading_skeleton
       expect(page).to have_no_css("[data-id='#{unloaded_message.id}']")
 
-      channel.send_message("test_message")
+      find(".chat-composer-input").fill_in(with: "test message")
+      find(".send-btn").click
 
       expect(channel).to have_no_loading_skeleton
       expect(page).to have_css("[data-id='#{unloaded_message.id}']")

plugins/chat/spec/system/jit_messages_spec.rb

@@ -6,7 +6,6 @@ RSpec.describe "JIT messages", type: :system, js: true do
   fab!(:other_user) { Fabricate(:user) }
 
   let(:chat) { PageObjects::Pages::Chat.new }
-  let(:channel) { PageObjects::Pages::ChatChannel.new }
 
   before do
     Jobs.run_immediately!
@@ -18,7 +17,8 @@ RSpec.describe "JIT messages", type: :system, js: true do
   context "when mentioning a user not on the channel" do
     it "displays a mention warning" do
       chat.visit_channel(channel_1)
-      channel.send_message("hi @#{other_user.username}")
+      find(".chat-composer-input").fill_in(with: "hi @#{other_user.username}")
+      find(".send-btn").click
 
       expect(page).to have_content(
         I18n.t("js.chat.mention_warning.without_membership.one", username: other_user.username),
@@ -37,7 +37,9 @@ RSpec.describe "JIT messages", type: :system, js: true do
 
     it "displays a mention warning" do
       chat.visit_channel(private_channel_1)
-      channel.send_message("hi @#{other_user.username}")
+      find(".chat-composer-input").fill_in(with: "hi @#{other_user.username}")
+      find(".chat-composer-input").click
+      find(".send-btn").click
 
       expect(page).to have_content(
         I18n.t("js.chat.mention_warning.cannot_see.one", username: other_user.username),
@@ -51,7 +53,8 @@ RSpec.describe "JIT messages", type: :system, js: true do
 
       it "displays a mention warning" do
         chat.visit_channel(channel_1)
-        channel.send_message("hi @#{group_1.name}")
+        find(".chat-composer-input").fill_in(with: "hi @#{group_1.name}")
+        find(".send-btn").click
 
         expect(page).to have_content(
           I18n.t("js.chat.mention_warning.group_mentions_disabled.one", group_name: group_1.name),

plugins/chat/spec/system/page_objects/chat/chat_channel.rb

@@ -12,7 +12,7 @@ module PageObjects
       end
 
       def click_send_message
-        find(".chat-composer .send-btn:enabled").click
+        find(".chat-composer .send-btn").click
       end
 
       def message_by_id(id)

plugins/chat/spec/system/transcript_spec.rb

@@ -173,14 +173,15 @@ RSpec.describe "Quoting chat message transcripts", type: :system, js: true do
     context "when quoting a message in another message" do
       fab!(:message_1) { Fabricate(:chat_message, chat_channel: chat_channel_1) }
 
-      xit "quotes the message" do
+      it "quotes the message" do
         chat_page.visit_channel(chat_channel_1)
 
         expect(chat_channel_page).to have_no_loading_skeleton
 
         clip_text = copy_messages_to_clipboard(message_1)
         click_selection_button("cancel")
-        chat_channel_page.send_message(clip_text)
+        chat_channel_page.fill_composer(clip_text)
+        chat_channel_page.click_send_message
 
         expect(page).to have_selector(".chat-message", count: 2)
 

spec/rails_helper.rb

@@ -245,7 +245,6 @@ RSpec.configure do |config|
       allow: [Webdrivers::Chromedriver.base_url]
     )
 
-    Capybara.threadsafe = true
     Capybara.disable_animation = true
 
     Capybara.configure do |capybara_config|