tmf: Drop the use of TmfFixedArray for statistics

tmf: Drop the use of TmfFixedArray for statistics

The same behaviour can be achieved by using straight [] arrays
and varargs methods. That way we don't need to instantiate new
wrapper objects all the time.

Unit tests were also updated.

Change-Id: I5f98ca2c08fd5bee5a1569c64466e63ef1e345d8
Signed-off-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Reviewed-on: https://git.eclipse.org/r/8264
Tested-by: Hudson CI
Reviewed-by: Patrick Tasse <patrick.tasse@gmail.com>
IP-Clean: Patrick Tasse <patrick.tasse@gmail.com>
Tested-by: Patrick Tasse <patrick.tasse@gmail.com>