Avoid dangerous file parsing and object serialization libraries.
yaml.load is the obvious function to use but it is dangerous[1]
Bandit flags yaml.load() as security risk so replace all occurrences
with yaml.safe_load().
[1]https://security.openstack.org/guidelines/dg_avoid-dangerous-input-parsing-libraries.html
Story: 1634265
Task: 38963
Change-Id: Ie5baf64696e6214e3dd01f6e06ede8fd8432cbb8