Enable proactive compaction back

[Boria138]

On arch wiki there is a warning that disabling proactive compaction causes performance degradation in games that use TCMalloc

Note that if your game uses TCMalloc (e.g., Dota 2 and CS:GO) then it is not recommended to disable THP as it comes with a large performance cost. Instead if you enable THP, you might also want to enable proactive compaction

[damentz]

For people that need proactive compaction, they can enable at any time through a sysctl. For the overwhelming number of other desktop and interactive use cases, proactive compaction is a net negative. We'll not be turning it back on by default.