Remove cs_CZ locale

Better to use default en_US locale.

Change-Id: I14b0393832fc99c767a3b1b6d35601291d9d8cf8
diff --git a/gerrit/server/single.yml b/gerrit/server/single.yml
index c279f00..f0f6492 100644
--- a/gerrit/server/single.yml
+++ b/gerrit/server/single.yml
@@ -61,7 +61,7 @@
         gerrit:
           enabled: true
           encoding: 'UTF8'
-          locale: 'cs_CZ'
+          locale: 'en_US'
           users:
           - name: gerrit
             password: ${_param:postgresql_gerrit_password}