[22841] Improve `max_allocations` calculation on SHM transport #1779

Job	Run time
sanitizers-ci / asan_fastdds_build	6m 35s
sanitizers-ci / tsan_fastdds_test	4h 0m 6s
sanitizers-ci / asan_fastdds_test	4h 58m 44s
sanitizers-ci / asan_discovery_server_test	5m 52s
	9h 11m 17s

Provide feedback