os.linux: Ignore testWriteToTsv swtbot test

This test causes instability in the SWTbot because of a potential race
condition with the update that changes the header column titles that do
not correspond to the system call data. The test should be modified
either to use SystemCall segments, or moved to timing.swtbot

Change-Id: Idea1c43f377ca79efb4bf5a4751f4611e6336891
Signed-off-by: Geneviève Bastien <gbastien+lttng@versatic.net>
Reviewed-on: https://git.eclipse.org/r/83967
Reviewed-by: Hudson CI
Reviewed-by: Matthew Khouzam <matthew.khouzam@ericsson.com>
Tested-by: Matthew Khouzam <matthew.khouzam@ericsson.com>