grails3-neo4j-hibernate example transaction fails on grails 4

[nathandunn]

Not sure if we should just use gorm-micronaut bindings everywhere instead for grails 4, but I wanted to provide these fixes either way.

• you can't run these embedded unless you change it from testRuntime to runtime

• I added a transaction here (weird), but removing static mapsWith = "neo4j" from the book class and updating the "show()" method int he BookController do the same thing.