shared/bus-util: use the new cleanup functionality to avoid a memleak

shared/bus-util: use the new cleanup functionality to avoid a memleak

If the async callbacks didn't get a chance to finish properly, we'd leak
memory.

The output from test-bus-util with additional log line in the callbacks to show
what is happening:

$ build/test-bus-util

/* test_name_async (0) */
Bus test-bus: changing state UNSET → OPENING
Bus test-bus: changing state OPENING → AUTHENTICATING
Bus test-bus: changing state AUTHENTICATING → HELLO
Sent message type=method_call sender=n/a destination=org.freedesktop.DBus path=/org/freedesktop/DBus interface=org.freedesktop.DBus member=Hello cookie=1 reply_cookie=0 signature=n/a error-name=n/a error-message=n/a
Sent message type=method_call sender=n/a destination=org.freedesktop.DBus path=/org/freedesktop/DBus interface=org.freedesktop.DBus member=RequestName cookie=2 reply_cookie=0 signature=su error-name=n/a error-message=n/a
Got message type=method_return sender=org.freedesktop.DBus destination=:1.732 path=n/a interface=n/a member=n/a cookie=4294967295 reply_cookie=1 signature=s error-name=n/a error-message=n/a
Bus test-bus: changing state HELLO → RUNNING
Bus test-bus: changing state RUNNING → CLOSED
request_name_destroy_callback n_ref=1

/* test_name_async (20) */
Bus test-bus: changing state UNSET → OPENING
Bus test-bus: changing state OPENING → AUTHENTICATING
Bus test-bus: changing state AUTHENTICATING → HELLO
stage 0: sd_bus_process returned 1
Sent message type=method_call sender=n/a destination=org.freedesktop.DBus path=/org/freedesktop/DBus interface=org.freedesktop.DBus member=Hello cookie=1 reply_cookie=0 signature=n/a error-name=n/a error-message=n/a
Sent message type=method_call sender=n/a destination=org.freedesktop.DBus path=/org/freedesktop/DBus interface=org.freedesktop.DBus member=RequestName cookie=2 reply_cookie=0 signature=su error-name=n/a error-message=n/a
stage 1: sd_bus_process returned 1
Got message type=method_return sender=org.freedesktop.DBus destination=:1.733 path=n/a interface=n/a member=n/a cookie=4294967295 reply_cookie=1 signature=s error-name=n/a error-message=n/a
Bus test-bus: changing state HELLO → RUNNING
stage 2: sd_bus_process returned 1
Got message type=signal sender=org.freedesktop.DBus.Local destination=n/a path=/org/freedesktop/DBus/Local interface=org.freedesktop.DBus.Local member=Connected cookie=4294967295 reply_cookie=0 signature=n/a error-name=n/a error-message=n/a
stage 3: sd_bus_process returned 1
Got message type=signal sender=org.freedesktop.DBus destination=:1.733 path=/org/freedesktop/DBus interface=org.freedesktop.DBus member=NameAcquired cookie=4294967295 reply_cookie=0 signature=s error-name=n/a error-message=n/a
stage 4: sd_bus_process returned 1
Got message type=error sender=org.freedesktop.DBus destination=:1.733 path=n/a interface=n/a member=n/a cookie=4294967295 reply_cookie=2 signature=s error-name=org.freedesktop.DBus.Error.AccessDenied error-message=Request to own name refused by policy
Unable to request name, will retry after reloading DBus configuration: Request to own name refused by policy
Sent message type=method_call sender=n/a destination=org.freedesktop.DBus path=/org/freedesktop/DBus interface=org.freedesktop.DBus member=ReloadConfig cookie=3 reply_cookie=0 signature=n/a error-name=n/a error-message=n/a
request_name_destroy_callback n_ref=2
stage 5: sd_bus_process returned 1
Got message type=method_return sender=org.freedesktop.DBus destination=:1.733 path=n/a interface=n/a member=n/a cookie=4294967295 reply_cookie=3 signature= error-name=n/a error-message=n/a
Sent message type=method_call sender=n/a destination=org.freedesktop.DBus path=/org/freedesktop/DBus interface=org.freedesktop.DBus member=RequestName cookie=4 reply_cookie=0 signature=su error-name=n/a error-message=n/a
request_name_destroy_callback n_ref=1
stage 6: sd_bus_process returned 1
Got message type=error sender=org.freedesktop.DBus destination=:1.733 path=n/a interface=n/a member=n/a cookie=4294967295 reply_cookie=4 signature=s error-name=org.freedesktop.DBus.Error.AccessDenied error-message=Request to own name refused by policy
Unable to request name, failing connection: Request to own name refused by policy
Bus test-bus: changing state RUNNING → CLOSING
stage 7: sd_bus_process returned 1
Bus test-bus: changing state CLOSING → CLOSED
stage 8: sd_bus_process returned 1
stage 9: sd_bus_process returned -104
Processing failed: Connection reset by peer