Extract capybara max wait time to env var

What does this MR do and why?

Extract capybara max wait time to env var, instead of hardcode value 10 in qa/qa/runtime/browser.rb

# before
      CAPYBARA_MAX_WAIT_TIME = 10
      Chemlab.configure do |config|
          config.browser = Capybara.current_session.driver.browser # reuse Capybara session
          config.libraries = [GitlabHandbook]
          config.base_url = Runtime::Scenario.attributes[:gitlab_address] # reuse GitLab address
          config.hide_banner = true
        end

# after

CAPYBARA_MAX_WAIT_TIME = Env.max_capybara_wait_time

def max_capybara_wait_time
  ENV.fetch('MAX_CAPYBARA_WAIT_TIME', 10).to_i
end

it seems we set max_wait_time to 60 in all places except in browser.rb file, eg

# repeater.rb
module QA
  module Support
    module Repeater
      using Rainbow
      DEFAULT_MAX_WAIT_TIME = 60


# in wait_for_requests.rb
module QA
  module Support
    module WaitForRequests
      module_function

      DEFAULT_MAX_WAIT_TIME = 60

# in capybara.rb
# Give CI some extra time
timeout = ENV['CI'] || ENV['CI_SERVER'] ? 60 : 30
Capybara.default_max_wait_time = timeout

If we set 10 in browser.rb, it will make capybara network timeout sometimes in JH pipeline, eg

        # in qa/qa/scenario/template.rb
        Runtime::Browser.configure! # set max wait time to 10 

        #
        # Perform before hooks, which are different for CE and EE
        #
        QA::Runtime::Release.perform_before_hooks unless QA::Runtime::Env.dry_run
        
        # in qa/qa/ce/strategy.rb
        QA::Support::Retrier.retry_on_exception do
          # it will timeout sometimes in JH pipeline because timeout is 10
          QA::Runtime::Browser.visit(:gitlab, QA::Page::Main::Login)
        end

/cc @daveliu