JvmtiBreakpoints are walked via VMThread oops_do (the breakpoint is in a vm operation) before they are installed in the safeopint and after they have been installed, walked with JvmtiCurrentBreakpoints::oops_do().
By putting the class holder inside oopStorage there is no need for this.

JvmtiCurrentBreakpoints::metadata_do is not needed because redefine classes actually removes the breakpoints before updating them (so there is no breakpoints to update).
We can just remove metadata_do.