limit openqa cache 150G (200G was too much)

hosts/osuosl167-amd64/etc/openqa/workers.ini

@@ -11,7 +11,7 @@ HOST = https://openqa.debian.net
 # Additionally you need to define the rsync URI to get
 # /var/lib/openqa/tests/ (TESTPOOLSERVER) in the webui section
 CACHEDIRECTORY = /var/lib/openqa/cache
-CACHELIMIT = 200 # GB, default is 50.
+CACHELIMIT = 150 # GB, default is 50.
 
 # hostname or IP address under which the worker is reachable by the web UI
 # (required by the web UI's developer mode to communicate with os-autoinst