修复gitlab管理中心的runner打开显示500的错误

迁移gitlab进行数据恢复之后，gitlab的管理中心的runner不能打开，显示500

查看日志显示:

Started GET "/admin/runners" for 10.148.60.33 at 2020-09-26 06:15:17 +0000
Processing by Admin::RunnersController#index as HTML
Completed 500 Internal Server Error in 10ms (ActiveRecord: 1.3ms)
  
ActionView::Template::Error ():
    37: 
    38:     .col-sm-6
    39:       .bs-callout
    40:         = render partial: ci/runner/how_to_setup_runner,
    41:                  locals: { registration_token: Gitlab::CurrentSettings.runners_registration_token,
    42:                            type: shared,
    43:                            reset_token_url: reset_registration_token_admin_application_settings_path }
  
lib/gitlab/crypto_helper.rb:27:in `aes256_gcm_decrypt
app/models/concerns/token_authenticatable_strategies/encrypted.rb:45:in `get_token
app/models/concerns/token_authenticatable_strategies/base.rb:33:in `ensure_token!
app/models/concerns/token_authenticatable.rb:45:in `block in add_authentication_token_field
app/models/application_setting_implementation.rb:218:in `runners_registration_token

原因是： 秘钥在读取的时候发生错误导致的，可以尝试进行重置runner_registration_token进行恢复，前提是之前的秘钥会丢失

解决办法是：

# 进入console
gitlab-rails console
# 重置token
ApplicationSetting.current.reset_runners_registration_token!
# 退出
exit

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