platform/local/tpm: create swtpm socket in temp directory under /tmp

[zhijianli88]

The swtpm unix socket was created relative to the test output directory under _kola_temp/, which triggers AppArmor denials for the swtpm profile on systems with AppArmor enabled:

• mantle debug log:
  2026-06-10T08:40:19Z util: dnsmasq-dhcp[30]: RTR-SOLICIT(kola-2616517) 6e:2a:7b:93:45:aa
  === RUN cl.tpm.eventlog 2026-06-10T08:40:22Z platform/local: Prepared swtpm process "/usr/bin/swtpm socket --tpmstate dir=./tpm --ctrl type=unixio,path=./tpm/socket --tpm2" with CWD "_kola_temp/qemu-2026-06-10-0840-13/cl.tpm.eventlog/e2eba778-2553-4563-a150-2e2e40d61639"
  2026-06-10T08:40:22Z platform/local: swtpm PID: 40
  2026-06-10T08:40:22Z util: swtpm: Could not open UnixIO socket: Permission denied
  2026-06-10T08:40:22Z platform: disabling auto-read-only for QEMU drives
  2026-06-10T08:40:22Z platform/machine/qemu: NewMachine: ["qemu-system-aarch64" "-machine" "virt" "-cpu" "cortex-a57" "-m" "2512" "-smp" "4" "-uuid" "e2eba778-2553-4563-a150-2e2e40d61639" "-display" "none" "-chardev" "file,id=log,path=console.txt" "-serial" "chardev:log" "-object" "rng-random,filename=/dev/urandom,id=rng0" "-device" "virtio-rng-pci,rng=rng0" "-drive" "if=pflash,unit=0,file=/work/build/images/images/arm64-usr/latest/flatcar_production_qemu_uefi_efi_code.qcow2,format=qcow2,readonly=on" "-drive" "if=pflash,unit=1,file=flatcar_production_qemu_uefi_efi_vars.qcow2,format=qcow2" "-chardev" "socket,id=chrtpm,path=tpm/socket" "-tpmdev" "emulator,id=tpm0,chardev=chrtpm" "-device" "tpm-tis-device,tpmdev=tpm0" "-fw_cfg" "name=opt/org.flatcar-linux/config,file=ignition.json" "-add-fd" "fd=3,set=1" "-drive" "if=none,id=d3,format=qcow2,file=/dev/fdset/1,auto-read-only=off" "-device" "virtio-blk-device,drive=d3,serial=primary-disk,bootindex=1" "-netdev" "tap,id=tap,fd=4" "-device" "virtio-net-device,netdev=tap,mac=02:00:00:00:00:02"], cwd: "_kola_temp/qemu-2026-06-10-0840-13/cl.tpm.eventlog/e2eba778-2553-4563-a150-2e2e40d61639", "10.0.0.2", "10.0.0.2"
  2026-06-10T08:40:22Z platform/machine/qemu: qemu PID (manual cleanup needed if --remove=false): 50
  qemu-system-aarch64: -chardev socket,id=chrtpm,path=tpm/socket: Failed to connect to 'tpm/socket': No such file or directory
  2026-06-10T08:40:23Z util: dnsmasq-dhcp[30]: RTR-SOLICIT(kola-2616517) 6e:2a:7b:93:45:aa
  2026-06-10T08:40:28Z util: dnsmasq-dhcp[30]: RTR-ADVERT(br0) fd00::

• host kernel audit:
  journalctl -xe | grep 'DENIED.*swtpm' | tail -n 20 Jun 10 17:40:22 ledyba kernel: audit: type=1400 audit(1781080822.038:163): apparmor="DENIED" operation="mknod" class="file" profile="swtpm" name="/work/TESTS/qemu_uefi/_kola_temp/qemu-2026-06-10-0840-13/cl.tpm.eventlog/e2eba778-2553-4563-a150-2e2e40d61639/tpm/socket" pid=1828693 comm="swtpm" requested_mask="c" denied_mask="c" fsuid=0 ouid=0 Jun 10 17:43:39 ledyba kernel: audit: type=1400 audit(1781081019.925:164): apparmor="DENIED" operation="mknod" class="file" profile="swtpm" name="/work/TESTS/qemu_uefi/_kola_temp/qemu-2026-06-10-0840-13/cl.tpm.eventlog/e2eba778-2553-4563-a150-2e2e40d61639/tpm/socket" pid=1828926 comm="swtpm" requested_mask="c" denied_mask="c" fsuid=0 ouid=0 Jun 10 17:43:47 ledyba kernel: audit: type=1400 audit(1781081027.251:165): apparmor="DENIED" operation="mknod" class="file" profile="swtpm" name="/work/TESTS/qemu_uefi/_kola_temp/qemu-2026-06-10-0840-13/cl.tpm.eventlog/e2eba778-2553-4563-a150-2e2e40d61639/tpm/socket" pid=1828943 comm="swtpm" requested_mask="c" denied_mask="c" fsuid=0 ouid=0

The test runs inside a container managed by run_local_tests.sh which mounts the current directory into the container. The socket created under the mounted directory is subject to the host's AppArmor policy for the swtpm profile.

Create the socket in a temporary directory under /tmp/ instead, using os.MkdirTemp. This avoids the AppArmor restriction and prevents collisions between concurrent test runs.

The SocketRelativePathFromTestDir method is renamed to SocketPath and now returns an absolute path, since the socket is no longer placed relative to the test directory.

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