Increase disk limit per job

I think some jobs are hitting the disk limit during git repo prep.

Increase it since we appear to have sufficient space.

Change-Id: Ie0e104ce476330a500765318b0cd9e65be56e937
diff --git a/zuul/zuul.conf b/zuul/zuul.conf
index a8197e7..3956404 100644
--- a/zuul/zuul.conf
+++ b/zuul/zuul.conf
@@ -18,7 +18,7 @@
 [executor]
 private_key_file=/var/lib/zuul/ssh/nodepool_id_rsa
 trusted_ro_paths=/authdaemon/token
-disk_limit_per_job=1000
+disk_limit_per_job=2000
 
 [database]
 dburi=mysql+pymysql://zuul:{{ zuul_deploy.db_password }}@mariadb-mariadb.mariadb/zuul