Maintenance: Remove change-minimizing MemObject::Io hack #234

Job	Run time
functionality-tests	18m 59s
source-maintenance-tests	2m 51s
CodeQL-tests	27m 45s
build-tests(ubuntu-22.04,gcc,default)	13m 12s
build-tests(ubuntu-22.04,gcc,minimal)	6m 39s
build-tests(ubuntu-22.04,gcc,maximus)	14m 19s
build-tests(ubuntu-22.04,clang,default)	14m 24s
build-tests(ubuntu-22.04,clang,minimal)	8m 23s
build-tests(ubuntu-22.04,clang,maximus)	16m 7s
	2h 2m 39s

Provide feedback