sdbusplus: remove deprecated --enable-transaction

sdbusplus removed support for disabling transaction IDs and
deprecated the --enable-transaction configure flag.  Remove
it here as well.

(From meta-phosphor rev: 3e13720e24f574e4b943032549707a6854e72303)

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ie3efd0ba4366e3bfc9b5fc5db27bcc182d95f7aa
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>