This change serializes write access to the policy database via the
AUthorative TOSCA provider by making sure that only one request is
executed at a time. His change should be repolaced by proper session
handling in the next release of the Policy Framework project.
Issue-ID: POLICY-2533
Change-Id: I5fe4c0f2846981a66eb2f4e1da936fe3c9490ae5
Signed-off-by: liamfallon <liam.fallon@est.tech>