qemu: pass task resources into driver for cgroup setup

As part of the work for 1.7.0 we moved portions of the task cgroup setup down
into the executor. This requires that the executor constructor get the
`TaskConfig.Resources` struct, and this was missing from the `qemu` driver. We
fixed a panic caused by this change in #19089 before we shipped, but this fix
was effectively undo after we added plumbing for custom cgroups for `raw_exec`
in 1.8.0. As a result, running `qemu` tasks always fail on Linux.

This was undetected in testing because our CI environment doesn't have QEMU
installed. I've got all the unit tests running locally again and have added QEMU
installation when we're running the drivers tests.

Fixes: #23250

.changelog/23466.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+qemu: Fixed a bug that prevented `qemu` tasks from running on Linux
+```

.github/workflows/test-core.yaml

@@ -114,6 +114,11 @@ jobs:
     steps:
       - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
       - uses: hashicorp/setup-golang@v3
+
+      - name: Install optional dependencies
+        if: ${{ matrix.groups == 'drivers' }}
+        run: sudo apt install qemu-system
+
       - name: Run Matrix Tests
         env:
           GOTEST_GROUP: ${{matrix.groups}}

drivers/qemu/driver.go

@@ -585,6 +585,7 @@ func (d *Driver) StartTask(cfg *drivers.TaskConfig) (*drivers.TaskHandle, *drive
 		StdoutPath:       cfg.StdoutPath,
 		StderrPath:       cfg.StderrPath,
 		NetworkIsolation: cfg.NetworkIsolation,
+		Resources:        cfg.Resources.Copy(),
 	}
 	ps, err := execImpl.Launch(execCmd)
 	if err != nil {