DAOS-16457 test: remove display_memory_info (#15031)

[daltonbohning]

display_memory_info was added to debug an issue when starting the servers, but resolved by #14295.
It is no longer needed and consumes too much log space and time.

Test-tag: test_basic_coverage
Skip-unit-tests: true
Skip-fault-injection-test: true

Required-githooks: true

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[github-actions]

Ticket title is 'ftest: remove display_memory_info()'
Status is 'Awaiting backport'
Job should run at elevated priority (1)
https://daosio.atlassian.net/browse/DAOS-16457