Revert "Revert "Revert "Merge branch 'sam_multiple_index_writes' into sam_multiple_iii_better"""

This reverts commit 70412e6ab2d2202999f40a33fa4f76de9f927877.

Conflicts:

	src/buffer_cache/alt/page_cache.hpp
Revert "Revert "Revert "Revert "Merge branch 'sam_multiple_index_writes' into sam_multiple_iii_better""""

This reverts commit 48a6864992d9be625e4ffcda8a4b669e36799646.