fix(messenger): fix fetch pageId when in live mode

[samuelmasse]

Fixes a problem where having a bot in live mode wouldn't work if it wasn't approved by facebook.

Closes DEV-1950

[linear]

DEV-1950 [BUG] Messenger stops working when the botpress server restarts while Facebook app is in live mode (botpress/borpress botpress/v12#1525)

If I restart the botpress server while the Facebook App it is connected to is in Live Mode, Messenger stops working receiving messages from the bot but it is still successfully sending messages to the bot.

I see the following error messages repeated in the logs

10/27/2021 11:19:32.395 [Messaging] app:messenger Error trying to setup conduit. Error: Error occured fetching page id
    at MessengerClient.getPageId (/snapshot/messaging/packages/server/dist/channels/messenger/client.js)
    at processTicksAndRejections (internal/process/task_queues.js:97:5)

If I put the Facebook app into Development Mode, I see the following success message

[Messaging] app:messenger [botname] Messenger webhook https://[www.website.com]/api/v1/messaging/webhooks/[botname]/messenger`

Turning the Facebook App back into Live Mode no longer shows the error message and Messenger starts working again.

I am running botpress on Ubuntu 18 through docker-compose: docker-compose-community-nginx-https.yaml.

botpress/borpress botpress/v12#1525 by @ imperialleisure

[franklevasseur]

LGTM