DAOS-18589 cart: test cleanup

[frostedcmos]

• few issues fixed in multisend:
  • bulk wasnt freed properly in some test modes
  • not specifying sync or async modes resulted before in a mixture
• dua_iface_server no longer overwrites D_LOG_MASK if it was already set
• self_test no longer sets self rank when running as a controller app, avoiding error printout when running with --master-endpoint argument

Steps for the author:

• Commit message follows the guidelines.
• Appropriate Features or Test-tag pragmas were used.
• Appropriate Functional Test Stages were run.
• At least two positive code reviews including at least one code owner from each category referenced in the PR.
• Testing is complete. If necessary, forced-landing label added and a reason added in a comment.

After all prior steps are complete:

• Gatekeeper requested (daos-gatekeeper added as a reviewer).

[github-actions]

Ticket title is 'multisend test cleanup'
Status is 'In Progress'
https://daosio.atlassian.net/browse/DAOS-18589

[daosbuild3]

Test stage NLT on EL 8.8 completed with status UNSTABLE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net/job/daos-stack/job/daos//view/change-requests/job/PR-17541/2/testReport/