DAOS-16768 pool: larger ABT ULT stack sizes

[kccain]

With this change, three ULTs in pool and container code launched via ds_pool_thread_collective() are changed to specify a larger ("deep") stack size of 64KiB rather than a default 16KiB stack size. i.e., the flags parameter specified as DSS_ULT_DEEP_STACK. The three ULT function entrypoints are:
cont_open_one, cont_snap_update_one,and update_vos_prop_on_targets.

Before this change, intermittently in CI testing, shortly after daos_engine startup, a dmg pool list (pool query on the back end) would occasionally result in a segmentation fault in an engine, in these three particular areas of the code. Specifically, the faults occurred within the ABT thread create, inside ABTI_mem_pool_alloc().

This change is based on a guess that the stack size parameter may have some effect.

Features: pool container test_engine_restart

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[github-actions]

Ticket title is 'server/daos_server_restart.py:DaosServerTest.test_engine_restart - test timeout - pool list takes 300 seconds'
Status is 'Open'
Labels: '2.6.2tb2,2.6.3rc1,2.7.101tb,ci_2.6_daily,ci_master_daily,daily_test'
https://daosio.atlassian.net/browse/DAOS-16768