ci: cleanup electron dirs after running tests on arm (#29769)
ci: cleanup electron dirs after running tests on arm (#29769)

* ci: cleanup electron dirs after running tests on arm

(cherry picked from commit 1c0a6045fbae8f9111fdd92730e5a81652e5a911)

* use start-stop-daemon to kill Xvfb
gerhardberger/electron,gerhardberger/electron,electron/electron,gerhardberger/electron,electron/electron,electron/electron,electron/electron,gerhardberger/electron,electron/electron,electron/electron,gerhardberger/electron,gerhardberger/electron,electron/electron,gerhardberger/electron