Since row_cache::populate() uses allocating_section now, the trick
with populating under relcaim lock no longer works, resulting in
assertion failure inside allocating_section:
row_cache_alloc_stress: utils/logalloc.hh:289: auto logalloc::allocating_section::operator()(logalloc::region&, Func&&) [with Func = row_cache::populate(const mutation&)::<lambda()>::<lambda()>]: Assertion `r.reclaiming_enabled()' failed.
Use the trick with populating until eviction is detected by comapring
region occupancy.