DAOS-16645 cart: Bump file descriptor limit (#15224)

[jolivier23]

With tcp provider, using many sockets can cause significant file descriptor usage. Bump the soft limit, if possible and warn if it appears insufficient.
Valgrind sets hard limit to soft limit, so work around that in NLT.

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[github-actions]

Ticket title is 'Automatically bump soft file descriptor limit for tcp provider'
Status is 'Awaiting backport'
Labels: 'google-cloud-daos'
Job should run at elevated priority (1)
https://daosio.atlassian.net/browse/DAOS-16645

[daosbuild1]

Test stage Functional Hardware Medium completed with status FAILURE. https://build.hpdd.intel.com//job/daos-stack/job/daos/view/change-requests/job/PR-15366/2/execution/node/1519/log

[daosbuild1]

Test stage NLT on EL 8.8 completed with status UNSTABLE. https://build.hpdd.intel.com/job/daos-stack/job/daos//view/change-requests/job/PR-15366/4/testReport/

[daosbuild1]

Test stage NLT on EL 8.8 completed with status UNSTABLE. https://build.hpdd.intel.com/job/daos-stack/job/daos//view/change-requests/job/PR-15366/5/testReport/

[daosbuild1]

Test stage NLT on EL 8.8 completed with status UNSTABLE. https://build.hpdd.intel.com/job/daos-stack/job/daos//view/change-requests/job/PR-15366/6/testReport/

[jolivier23]

Looks like 2.6 branch needs some valgrind backports to suppress go errors.

[daltonbohning]

This might be safe since it's a backport, but this PR does modify utils/node_local_test.py and NLT is failing

[daltonbohning]

Looks like 2.6 branch needs some valgrind backports to suppress go errors.

To fix NLT?

[jolivier23]

Looks like 2.6 branch needs some valgrind backports to suppress go errors.

To fix NLT?

yes, we are probably missing some valgrind backports

This might be safe since it's a backport, but this PR does modify utils/node_local_test.py and NLT is failing

It doesn't fundamentally change NLT though. It just bumps the file descriptor limit to avoid a warning.

[daltonbohning]

FWIW we did just land this backport
79bf081

But if you're reasonable confident this PR is safe, no objection from me