Fix critical Sonar Issue: ConfigurationServiceImpl.java

Fix critical Sonar Issue: ConfigurationServiceImpl.java

Fix for the following issue:
- Throwable.printStackTrace(...) should never be called

https://sonar.opendaylight.org/component/index#component=org.opendaylight.ovsdb%3Aplugin%3Amaster%3Asrc%2Fmain%2Fjava%2Forg%2Fopendaylight%2Fovsdb%2Fplugin%2Fimpl%2FConfigurationServiceImpl.java&settings=issues&blocks=959%2C967&tab=issues&item=.js-filter-CRITICAL-issues&line=963

patch 2: replace 'e.fillInStackTrace()' with 'e'
patch 3: set log level to error

Change-Id: I91af7d1548b3c7563126ace9ad33a0f1b8877379
Signed-off-by: Flavio Fernandes <ffernand@redhat.com>