executor: set CpuWeight in cgroup-v2 (#11287)

Cgroup-v2 uses `cpu.weight` property instead of cpu shares:
https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html#cpu-interface-files
. And it uses a different range (i.e. `[1, 10000]`) from cpu.shares
(i.e. `[2, 262144]`) to make things more interesting.

Luckily, the libcontainer provides a helper function to perform the
conversion
[`ConvertCPUSharesToCgroupV2Value`](https://pkg.go.dev/github.com/opencontainers/runc@v1.0.2/libcontainer/cgroups#ConvertCPUSharesToCgroupV2Value).

I have confirmed that docker/libcontainer performs the conversion as
well in
https://github.com/opencontainers/runc/blob/v1.0.2/libcontainer/specconv/spec_linux.go#L536-L541
, and that CpuShares is ignored by libcontainer in
https://github.com/opencontainers/runc/blob/v1.0.2/libcontainer/cgroups/fs2/cpu.go#L24-L29
.

.changelog/11287.txt

@@ -0,0 +1,4 @@
+
+```release-note:bug
+driver/exec: Set CPU resource limits when cgroup-v2 is enabled
+```

drivers/shared/executor/executor_linux.go

@@ -687,8 +687,9 @@ func configureCgroups(cfg *lconfigs.Config, command *ExecCommand) error {
 		return fmt.Errorf("resources.Cpu.CpuShares must be equal to or greater than 2: %v", cpuShares)
 	}
 
-	// Set the relative CPU shares for this cgroup.
+	// Set the relative CPU shares for this cgroup, and convert for cgroupv2
 	cfg.Cgroups.Resources.CpuShares = uint64(cpuShares)
+	cfg.Cgroups.Resources.CpuWeight = cgroups.ConvertCPUSharesToCgroupV2Value(uint64(cpuShares))
 
 	return nil
 }