api/compaction_manager: do not hold map on the stack
api/compaction_manager: do not hold map on the stack

Merged patch series by Amnon Heiman:

This patch fixes a bug that a map is held on the stack and then is used
by a future.

Instead, the map is now moved to the relevant lambda function.

Fixes #4824

scylladb/scylla,avikivity/scylla,avikivity/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla,avikivity/scylla