build(deps): bump cilium to v0.21.0

[ningmingxiao]

go tool nm -size -sort=size containerd-shim-runc-v2

 c4eda0   33554432 D crypto/internal/fips140/drbg.memory
  b64220     472384 r go:func.*
  c22220      93464 D runtime.mheap_
  c3dda0      69632 D runtime.cgroupScratch
  681780      25588 T github.com/cilium/ebpf/btf.readAndInflateTypes
  780a60      19592 T crypto/internal/fips140/sha3.keccakF1600.abi0
  bd7760      18168 r runtime.findfunctab
  c1e360      16064 D runtime.semtable

go tool nm -size -sort=size cgctl
  bad2c0      93320 D runtime.mheap_
  bc8220      69632 D runtime.cgroupScratch
  594fe0      24236 T github.com/cilium/ebpf/btf.readAndInflateTypes
  763ce0      19592 T crypto/internal/fips140/sha3.keccakF1600.abi0
  8e3320      17596 r runtime.findfunctab
  ba9400      16064 D runtime.semtable
  56c2e0      14132 T debug/elf.NewFile
  6350c0      13005 T google.golang.org/protobuf/internal/impl.fieldCoder
  8f98e0      11748 r runtime.typelink

I find btf.readAndInflateTypes use about 25KB
after this pr

go tool nm -size -sort=size cgctl
  c07440      93320 D runtime.mheap_
  c223a0      69632 D runtime.cgroupScratch
  78ff00      19592 T crypto/internal/fips140/sha3.keccakF1600.abi0
  924260      18478 r runtime.findfunctab
  5be6e0      17514 T github.com/cilium/ebpf/btf.(*decoder).inflateType
  c03580      16064 D runtime.semtable
  55ed80      14132 T debug/elf.NewFile