Exclude Category-X JDBC drivers from binary distribution

The binary distribution contains all the required elements to be able to run Hive in a cluster. It can be obtained by building from source using the following command:

mvn clean package -DskipTests -Pdist

The binary distribution is also published during a release along with the source code.
 
In current master, commit 8572c1201e1d483eb03c7e413f4ff7f9b6f4a3d2, the binary distribution includes the following JDBC drivers:

• derby-10.14.1.0.jar
• postgresql-42.2.14.jar
• ojdbc8-21.3.0.0.jar
• mssql-jdbc-6.2.1.jre8.jar
• mysql-connector-java-8.0.27.jar

JDBC drivers are needed:

• by schemaTool to initialize the database backend for the Metastore
• by metastore to communicate with underlying database
  so if we want Hive to work out of the box we have to provide at least one.

The Oracle (ojdbc8) and MySQL (mysql-connector-java) drivers must be removed cause their license is not compatible with Apache License 2 (see category x).

Previous Hive releases (e.g., 3.1.2) are not affected since they only contain:

• derby-10.14.1.0.jar
• postgresql-9.4.1208.jre7.jar

The additional drivers that appear in the binary distribution are a side effect of HIVE-25701.