[CVP-Sanity] Override nested params of global config in Jenkins

Added possibility to overwrite the nested parameters (dictionaries)
in Jenkins. Jenkins EXTRA_PARAMS will have the "override_config"
key which is passed to python tests as env var. Then it overrides
partially/fully the options in test config in YAML format.
Added the example in YAML format.

Depends on:
https://gerrit.mcp.mirantis.com/#/c/54895/
https://gerrit.mcp.mirantis.com/#/c/54893/

Change-Id: I419f567f85bedcee04272ec55626e2d8404b35fd
Related-Prod: PROD-29371
1 file changed