Stop the version sync running in every child module

preparationGoals runs across the whole reactor, so the inherited execution
resolved ${basedir} to each child and release:prepare died on
modules/resource-bundle/modules/samples/userguide/src/userguide not existing.
Marked not inherited: children get the goal with no target and do nothing, and
the rewrite happens once at the root. The release guide also now records that a
dry run cannot exercise this -- it never replaces pom.xml, so the goal sees the
SNAPSHOT version and writes it straight back.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>