Fix custom variable passing to tempest container

Commit e0ed6cac5c468952923dd8e655127a7295580ec6 has improved
quotation and this has broken run tempest method by replacing of
double quotes.

Change-Id: Ic918951257118b7772e29592d448c5eb98ab32e4
Related-Prod: https://mirantis.jira.com/browse/PROD-15932
1 file changed