postgres: Set `jit = off` on matrix.archlinux.org

This seems to be the cause for our memory leak.

https://www.postgresql.org/message-id/flat/16707-f5df308978a55bf8%40postgresql.org

playbooks/matrix.archlinux.org.yml

@@ -18,6 +18,7 @@
       postgres_work_mem: 32MB
       postgres_maintenance_work_mem: 32MB
       postgres_effective_cache_size: 2GB
+      postgres_jit: 'off'
     - role: postfix
       postfix_relayhost: "mail.archlinux.org"
     - { role: matrix }

roles/postgres/defaults/main.yml

@@ -12,6 +12,7 @@ postgres_shared_buffers: '128MB'
 postgres_work_mem: '4MB'
 postgres_maintenance_work_mem: '64MB'
 postgres_effective_cache_size: '4GB'
+postgres_jit: 'on'
 
 postgres_ssl_hosts4: []
 postgres_ssl_hosts6: []

roles/postgres/templates/postgresql.conf.j2

@@ -405,7 +405,7 @@ effective_cache_size = {{ postgres_effective_cache_size }}
 #join_collapse_limit = 8		# 1 disables collapsing of explicit
 					# JOIN clauses
 #force_parallel_mode = off
-#jit = on				# allow JIT compilation
+jit = {{ postgres_jit }}				# allow JIT compilation
 #plan_cache_mode = auto			# auto, force_generic_plan or
 					# force_custom_plan