Fix Redhat 4.x OS /proc/meminfo has no MemAvailable, disable MemAvailable to control memory. vm_rss_str and mem_available_str recorded when gc is triggered, to avoid memory changes during gc and cause inaccurate logs. join probe catch bad_alloc, this may alloc 64G memory at a time, avoid OOM. Modify document doris_be_all_segments_num and doris_be_all_rowsets_num names.