Remove references to RangerAuthorizationConfig due to changes in Ranger

Due to recent changes in https://issues.apache.org/jira/browse/RANGER-2646, the way Impala instantiates a Ranger authorization configuration in RangerAuthorizationConfig.java should change accordingly.

Two steps are thus required.

1. Remove the references to the class of RangerConfiguration in RangerAuthorizationConfig.java.
2. Instantiate rangerConfig_ using the class of RangerPluginConfig provided in the newer version of Ranger instead of RangerConfiguration as is done today ( https://github.com/apache/impala/blob/master/fe/src/main/java/org/apache/impala/authorization/ranger/RangerAuthorizationConfig.java#L38).

The second step requires us to bump up CDP_BUILD_NUMBER to 1626038 or a later number. Due to compatibility issues of Impala with other components in the toolchain, for now we just perform the first step. The second step will be implemented in a follow-up JIRA after we can be sure there will not be any compatibility issues after bumping up CDP_BUILD_NUMBER.