[SO] 16.0.3 release

[SO] 16.0.3 release

- update images of SO main repo (1.15.4 -> 1.15.5)
- support tracing for so-api-handler-infra
- make root log level configurable for so-api-handler-infra
- skip tracing for scheduled dns lookups and active client checks
- skip request status logging for /manage liveness endpoint
  (thus greatly reducing the log volume produced in debug log level)
- disable rbac for this release (not working in this release, will
  be fixed in the next one) [0]

[0] Since there is no role specific resource in the SO,
    there is currently effectively no difference between
    enabled or disabled anyways

Issue-ID: SO-4184
Change-Id: I22c43356614f983090eec112ecc017ad843f2d54
Signed-off-by: Fiete Ostkamp <Fiete.Ostkamp@telekom.de>