feat: send mailings over MailJet smtp in dedicated worker process

config/services.yaml

@@ -9,6 +9,13 @@ parameters:
 
     teamer_inactive_period: '-2 years'
 
+    # Messenger transport the mails of a teamer mailing are queued on. An X-Bus-Transport
+    # header wins over the routing in messenger.yaml (see SendersLocator::getSenders),
+    # so this is what keeps a mailing off the shared queue - and what has to be switched
+    # back to "sync" further down, or a mailing would need a running worker to arrive
+    # in dev and test while every other mail is sent right away.
+    mailing_bus_transport: 'mailing'
+
     # Dates (MM-DD) on which teamers must re-confirm their personal data.
     personal_data_check_deadlines:
         - '04-01'
@@ -51,6 +58,7 @@ services:
             $xmlExport: '@xml_export.storage'
             $xmlDump: '@xml_dump.storage'
             $teamerInactivePeriod: '%teamer_inactive_period%'
+            $mailingBusTransport: '%mailing_bus_transport%'
 
     App\:
         resource: '../src/'
@@ -243,3 +251,15 @@ services:
                 myep_oauth2_url_access_token: '%env(MYEP_OAUTH2_URL_ACCESS_TOKEN)%'
                 myep_oauth2_url_resource_owner_details: '%env(MYEP_OAUTH2_URL_RESOURCE_OWNER_DETAILS)%'
                 myep_oauth2_scopes: '%env(csv:MYEP_OAUTH2_SCOPES)%'
+
+# The mails of a mailing are sent right away here, like every other mail, instead of
+# waiting for a worker on the dedicated queue. The mailer transport is deliberately not
+# switched: a mailing still goes out over MAILING_MAILER_DSN, so the path being exercised
+# locally is the one that runs in production.
+when@dev:
+    parameters:
+        mailing_bus_transport: 'sync'
+
+when@test:
+    parameters:
+        mailing_bus_transport: 'sync'