Data wiping is on by default, for both MySQL and CQL
(not yet implemented for Postgresql) and but can be
overridden by KEA_TEST_DB_WIPE_DATA_ONLY.

src/lib/mysql/testutils/mysql_schema.*
    destroyMySQLSchema()
    createMySQLSchema() - added check of softWipeEnabled() to
    see if env var has turned it OFF.

Changed CQL to work the same way as MySQL:

src/share/database/scripts/cql
    wipe_data.sh.in - new file, replaces soft_wipe.cql

src/lib/cql/testutils/cql_schema.*
    destroyCqlSchema() - now destroys the schema
    if data wipe fails or is disabled

    createCqlSchema() - now drops/creates the schema
    if data wipe fails or is disabled.

    runCqlScript(() - added request-timeout to prevent
    timeout errors in slow environments

    wipeCqlData(bool show_err) - new function that
    attempts to run the wipe shell script

src/lib/dhcpsrv/tests/cql_lease_mgr_unittest.cc
    Removed now superflous destroyCqlSchema calls