Small refactoring for packer scripts

* Get rid of formula version variable and use MCP_VERSION instead
* Remove docker images pull
* Remove adding of jenkins theme b/c it's already inside docker image
* Move flag for jenkins in docker to /opt

Closes-task: #PROD-24048 (PROD:24048)
Change-Id: I41a1c4771d9cf890bd371264a35727ded6fc52a8
diff --git a/trymcp-day01-image/scripts/salt.sh b/trymcp-day01-image/scripts/salt.sh
index ed696f4..2161aaf 100644
--- a/trymcp-day01-image/scripts/salt.sh
+++ b/trymcp-day01-image/scripts/salt.sh
@@ -1,7 +1,7 @@
 #!/bin/bash -xe
 
-FORMULA_VERSION=${FORMULA_VERSION:-2018.3.1}
-APT_MIRANTIS_SALT_REPO=${APT_MIRANTIS_SALT_REPO:-"http://apt.mirantis.com/xenial/ $FORMULA_VERSION salt"}
+MCP_VERSION=${MCP_VERSION:-proposed}
+APT_MIRANTIS_SALT_REPO=${APT_MIRANTIS_SALT_REPO:-"http://apt.mirantis.com/xenial/ $MCP_VERSION salt"}
 SALT_OPTS="-t 10 --retcode-passthrough --no-color"
 
 echo "deb [arch=amd64] ${APT_MIRANTIS_SALT_REPO}" > /etc/apt/sources.list.d/mcp_salt.list