What were these bent clamps at the top of Apollo 11 CM used for?

That's the main parachute retention system in the Block II command modules.

The Block I main-parachute retention flaps were replaced by a series of fabric- covered, spring steel straps attached to the upper-deck structure. These straps were then chain-laced by an interlocking length of cord to loops sewed to the face of the main- parachute deployment bag (fig. A-12).

From Apollo Experience Report, Earth Landing Systems

Not labeled but shown here

From Apollo Spacecraft and Systems Familiarization training course (annotations mine)

Upper and lower sets of straps are visible in this section of the image from this question: Is it the Apollo CM "flowerpot parachute attachment fitting"?