Revert "Improve previous fix, only load from holders if explicitly told to in dev environment"

This reverts commit 4cabb31595989b13756c4a2b3e3c5ec592d1228b.
Revert "fix for GRAILS-10920 "Config gets executed multiple times""

This reverts commit 979de2894c439d4d3907477d52469546e41c95c6.
Merge branch '2.3.x' of github.com:grails/grails-core into 2.3.x