BpfMap.getOrCreate(size, path, type) -> BpfMap.init(path)

We don't have the appropriate selinux privs to create the maps anyway.

Test: builds (when combined with system/netd change)
      'git grep getOrCreate' in system/{bpf,netd} comes up empty
      atest netd_unit_test netd_integration_test libbpf_android_test
Bug: 65674744
Bug: 129654883
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Idffbce5b28b723943c6495cfafdecddc7a0f4e67