tmf: Use find() instead of matches() in TmfFilterMatchesNode

tmf: Use find() instead of matches() in TmfFilterMatchesNode

This removes the need for a regex fix to add .* before and after, and
ensures the highlighting is always correct even for complex expressions.

Change-Id: I0fd19b0c396861b68292e458cb0f2f67202561c9
Signed-off-by: Patrick Tasse <patrick.tasse@gmail.com>
Reviewed-on: https://git.eclipse.org/r/44278
Reviewed-by: Hudson CI
Reviewed-by: Bernd Hufmann <bernd.hufmann@ericsson.com>
Tested-by: Bernd Hufmann <bernd.hufmann@ericsson.com>