Fixed regression in TrendNode.

The regression was caused by change r32901 and merge r32981. The problem
was that the code tried to keep existing VertRuler nodes alive as much
as possible to keep their (transient) settings in place between chart
configuration reloads. However the code failed to do this correctly and
caused IndexOutOfBoundsExceptions and other corollary failures.

This fix needs to go into platform branches 1.22.2 and 1.22 as well.

refs #6547
[PRIVATE-11736]

Change-Id: Idb7d9d77b1a6b0bf513a5829b4c373cde9747529