common/pkg/cgroups: Remove unused fs imports and handler fields

The github.com/opencontainers/cgroups/fs import and associated struct
fields (Blkio, CPU, CPUSet, Mem, Pid) were never used in any of the
handler implementations. These were remnants from the cgroups v1 removal.

The empty handler structs are retained as they serve as method receivers
for implementing the controllerHandler interface.

Signed-off-by: Lokesh Mandvekar <[email protected]>

Author: lsm5

common/pkg/cgroups/blkio_linux.go

@@ -7,11 +7,9 @@ import (
 	"strings"
 
 	"github.com/opencontainers/cgroups"
-	"github.com/opencontainers/cgroups/fs"
 )
 
 type linuxBlkioHandler struct {
-	Blkio fs.BlkioGroup
 }
 
 func getBlkioHandler() *linuxBlkioHandler {

common/pkg/cgroups/cpu_linux.go

@@ -6,11 +6,9 @@ import (
 	"strconv"
 
 	"github.com/opencontainers/cgroups"
-	"github.com/opencontainers/cgroups/fs"
 )
 
 type linuxCPUHandler struct {
-	CPU fs.CpuGroup
 }
 
 func getCPUHandler() *linuxCPUHandler {

common/pkg/cgroups/cpuset_linux.go

@@ -4,11 +4,9 @@ package cgroups
 
 import (
 	"github.com/opencontainers/cgroups"
-	"github.com/opencontainers/cgroups/fs"
 )
 
 type linuxCpusetHandler struct {
-	CPUSet fs.CpusetGroup
 }
 
 func getCpusetHandler() *linuxCpusetHandler {

common/pkg/cgroups/memory_linux.go

@@ -6,11 +6,9 @@ import (
 	"path/filepath"
 
 	"github.com/opencontainers/cgroups"
-	"github.com/opencontainers/cgroups/fs"
 )
 
 type linuxMemHandler struct {
-	Mem fs.MemoryGroup
 }
 
 func getMemoryHandler() *linuxMemHandler {

common/pkg/cgroups/pids_linux.go

@@ -6,11 +6,9 @@ import (
 	"path/filepath"
 
 	"github.com/opencontainers/cgroups"
-	"github.com/opencontainers/cgroups/fs"
 )
 
 type linuxPidHandler struct {
-	Pid fs.PidsGroup
 }
 
 func getPidsHandler() *linuxPidHandler {