TMF: Fix behavior of XML time graph views with experiments

TMF: Fix behavior of XML time graph views with experiments

Expected behavior:
* Show the content of analyses when the trace contains those analyses.
* If experiment, show the content of analyses if any of the trace or
the experiment itself contains those analyses.
* Empty if no trace contains the required analyses.

Change-Id: Id04c2f9d4f1ecd9c8c466a9a0536e1b07277ea1f
Signed-off-by: Geneviève Bastien <gbastien+lttng@versatic.net>
Signed-off-by: Matthew Khouzam <matthew.khouzam@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/35490
Reviewed-by: Hudson CI