Fix db2 scanner module crashes

[adfoster-r7]

Fixes a uninitialized constant error crash with all ibm db2 modules

msf6 auxiliary(scanner/db2/db2_version) > run rhost=127.0.0.1

[-] 127.0.0.1:50000       - Auxiliary failed: NameError uninitialized constant Rex::Proto::DRDA::Utils::EXCSAT_DDM
Did you mean?  Rex::Proto::DRDA::EXCSAT_DDM
[-] 127.0.0.1:50000       - Call stack:
[-] 127.0.0.1:50000       -   /Users/user/Documents/code/metasploit-framework/lib/rex/proto/drda/utils.rb:13:in `client_probe'
[-] 127.0.0.1:50000       -   /Users/user/Documents/code/metasploit-framework/lib/msf/core/exploit/remote/db2.rb:41:in `db2_probe'
[-] 127.0.0.1:50000       -   /Users/user/Documents/code/metasploit-framework/modules/auxiliary/scanner/db2/db2_version.rb:34:in `run_host'
[-] 127.0.0.1:50000       -   /Users/user/Documents/code/metasploit-framework/lib/msf/core/auxiliary/scanner.rb:124:in `block (2 levels) in run'
[-] 127.0.0.1:50000       -   /Users/user/Documents/code/metasploit-framework/lib/msf/core/thread_manager.rb:105:in `block in spawn'
[*] Auxiliary module execution completed

Verification

Ensure the db2 scanner module no longer crashes

I put some cycles into getting db2 to work from docker, but didn't succeed in getting it to work with either msfconsole or intellij's database connector

# Doesn't seem to support remote connections by default?
sudo docker run -it --privileged=true -p 50000:50000 -e LICENSE=accept -e DB2INST1_PASSWORD=password -e DBNAME=testdb ibmcom/db2

# Works via docker though, after docker exec -it docker_id /bin/bash
su db2inst1
[db2inst1@898cf36794a5 config]$ db2 list db directory

 System Database Directory

 Number of entries in the directory = 1

Database 1 entry:

 Database alias                       = TESTDB
 Database name                        = TESTDB
 Local database directory             = /database/data
 Database release level               = 15.00
 Comment                              =
 Directory entry type                 = Indirect
 Catalog database partition number    = 0
 Alternate server hostname            =
 Alternate server port number         =

[dwelch-r7]

Release Notes

Fix db2 scanner module crashes