rootless: fix getCurrentOOMScoreAdj
rootless: fix getCurrentOOMScoreAdj

`getCurrentOOMScoreAdj()` was broken because `strconv.Atoi()` was called
without trimming "\n".

Fix issue 40068: `rootless docker in kubernetes: "getting the final child's pid from
pipe caused \"EOF\": unknown"

Signed-off-by: Akihiro Suda <10ddef0dea2a66ab193b07198faa879adcb213d8@hco.ntt.co.jp>

paralin/docker,nawawi/docker,gnailuy/docker,djs55/docker,nawawi/docker,djs55/docker,flavio/docker,Ramzec/docker,jameszhan/docker,thaJeztah/docker,bearstech/moby,docker/docker,paralin/docker,jimjag/docker,moby/moby,kojiromike/docker,Mokolea/docker,trebonian/docker,flavio/docker,cpuguy83/docker,docker/docker,yosifkit/docker,bearstech/moby,moul/docker,AkihiroSuda/docker,Ramzec/docker,kojiromike/docker,kojiromike/docker,Ramzec/docker,jameszhan/docker,bearstech/moby,moby/moby,jthelin/docker,moul/docker,AkihiroSuda/docker,AkihiroSuda/docker,trebonian/docker,jameszhan/docker,thaJeztah/docker,cpuguy83/docker,thaJeztah/docker,moul/docker,konstruktoid/docker-upstream,mahak/docker,nalind/docker,vdemeester/docker,konstruktoid/docker-upstream,Mokolea/docker,thaJeztah/docker,jimjag/docker,Mokolea/docker,trebonian/docker,AkihiroSuda/docker,Mokolea/docker,flavio/docker,nawawi/docker,nawawi/docker,mahak/docker,paralin/docker,yosifkit/docker,nalind/docker,vdemeester/docker,jthelin/docker,paralin/docker,trebonian/docker,jimjag/docker,gnailuy/docker,mahak/docker,gnailuy/docker,yosifkit/docker,yosifkit/docker,flavio/docker,moul/docker,mahak/docker,konstruktoid/docker-upstream,vdemeester/docker,bearstech/moby,moby/moby,nalind/docker,docker/docker,konstruktoid/docker-upstream,nalind/docker,djs55/docker,cpuguy83/docker,cpuguy83/docker,Ramzec/docker,gnailuy/docker,jimjag/docker,moby/moby