Changes

scripting: bug 565243 Remove extra label in time graph view

Trace Compass changed the way the label is drawn, so the text draw in
the postDrawEvent method is not necessary anymore.

Change-Id: I1c6e73325391bd9c29eca4f892a62fe5efd0b1c7
Signed-off-by: Geneviève Bastien <gbastien+lttng@versatic.net>
Reviewed-on: https://git.eclipse.org/r/c/tracecompass.incubator/org.eclipse.tracecompass.incubator/+/166455
Tested-by: Trace Compass Bot <tracecompass-bot@eclipse.org>
Tested-by: Matthew Khouzam <matthew.khouzam@ericsson.com>
Reviewed-by: David Piché <dpiche.veg@gmail.com>
Reviewed-by: Matthew Khouzam <matthew.khouzam@ericsson.com>