master: make volume capacity reservation timeout configurable (#11426) (#11497)

* master: make volume capacity reservation timeout configurable (#11426)

* master: expire reservations on reads, fix int timeout units

- AvailableSpaceForReservation now expires reservations too: a node that
  is full of reservations is filtered out before TryReserveCapacity can
  clean them, which stranded expired capacity indefinitely.
- Drop TryReserveCapacityWithTimeout: a per-call timeout lets one caller
  expire another's live reservations, and the Node interface stays
  stable for implementations outside this tree.
- parseReservationTimeout no longer routes integer values through
  GetDuration, which read them as nanoseconds; bare numbers are
  seconds. The 5m fallback is now the shared DefaultReservationTimeout.

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Co-authored-by: Chris Lu <chrislusf@users.noreply.github.com>

weed/command/scaffold/master.toml

@@ -41,6 +41,7 @@ copy_2 = 6                # create 2 x 6 = 12 actual volumes
 copy_3 = 3                # create 3 x 3 = 9 actual volumes
 copy_other = 1            # create n x 1 = n actual volumes
 threshold = 0.9           # create threshold
+reservation_timeout = "5m"# capacity reservation timeout before unreleased reservations expire
 disable = false           # disables volume growth if true
 
 # configuration flags for replication