HBASE-24019: Correct exception messages for table null and namespace unavailable. (#1312)

Signed-off-by: Pankaj <pankajkumar@apache.org>
Signed-off-by: Jan Hentschel <jan.hentschel@ultratendency.com>
Signed-off-by: Viraj Jasani <vjasani@apache.org>
2 files changed