The org.osbuild.chrony stage was extended to allow additional directives
alongside time servers [1]. The old Timeservers string slice was kept
for backwards compatibility. Removing support for it in
osbuild-composer makes working with the stage's options simpler. Using
the new struct slice Servers field and only specifying a Hostname for
each element is equivalent to the old behaviour, so no functionality is
lost.
This simplifies the chrony stage since no validation is required
anymore.
It also simplifies the propagation of configuration options through the
pipeline generation code which doesn't need to check for both types of
stage options.
[1] https://github.com/osbuild/osbuild/pull/692
5d760c48ad