Thunderbird and Seamonkey clients are not being served redirects to addons.thunderbird.net

[diox]

Per #4765 we should be redirecting some Thunderbird and Seamonkey URLs to https://addons.thunderbird.net/

However, when the User-Agent of the request is Thunderbird or Seamonkey, instead we serve it with addons-server and it's 500ing for some URLs that we've removed from addons-server.

The rewrite is visible here:
https://github.com/mozilla-services/cloudops-deployment/blob/b7dde84a0cad09b1d71efc651604b99acd7f18fe/projects/amo/puppet/modules/amo_proxy/templates/nginx.addons.conf.erb#L216-L219

However, a few lines above, to handle #11066 there is another bit of config that directly calls addons-server if the User Agent header is Thunderbird or Seamonkey: https://github.com/mozilla-services/cloudops-deployment/blob/b7dde84a0cad09b1d71efc651604b99acd7f18fe/projects/amo/puppet/modules/amo_proxy/templates/nginx.addons.conf.erb#L205-L210

That bit with the User-Agent detection should be removed.

Sentry traceback that helped us figure out that the requests were erroneously going to addons-server: https://sentry.prod.mozaws.net/operations/olympia-prod/issues/5328593/

[diox]

STR in simple commands:
curl -s https://addons.mozilla.org/es/thunderbird/ --user-agent "Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1" -I | fgrep -i Location

Expected results:
Location: https://addons.thunderbird.net/es/thunderbird/

Actual results:
Location: /es/firefox/thunderbird/

[bqbn]

The fix for this is deployed to -dev and -stage. Please test it.

[AlexandraMoga]

I've used a pref to override my current user agent - general.useragent.override set to "Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1"

https://addons.allizom.org/es/thunderbird/ redirects now to https://addons.thunderbird.net/es/thunderbird/

I've repeated the test for Seamonkey and that worked as well.

[diox]

Looks good to me.

[bqbn]

The fix is deployed to -prod as well.