Increase number of workers in preset 'iaas' from 4 to 16 (#1211)

These workers don't use a lot of resources except wall time

Signed-off-by: Matthias Büchse <matthias.buechse@alasca.cloud>

Author: mbuechse

Tests/config.toml

@@ -32,7 +32,7 @@ subjects = [
     "syseleven-ham1",
     "wavestack",
 ]
-workers = 4
+workers = 16
 
 
 [presets.kaas]