Revert "speculative workaround for high unclosed connection count bet…

…ween compute smgr & pageserver (#523)"

This reverts commit e5248b0.

neonvm/tools/vm-builder/main.go

@@ -260,13 +260,6 @@ action=/neonvm/bin/powerdown
 	scriptPowerDown = `#!/neonvm/bin/sh
 
 su -p postgres --session-command '/usr/local/bin/pg_ctl stop -D /var/db/postgres/compute/pgdata -m fast --wait -t 10'
-# The poweroff below is the busybox poweroff which goes straight to the kernel, i.e., LINUX_REBOOT_CMD_POWER_OFF / RB_POWER_OFF.
-# Our experiments have shown that, generally, this type of hard shutdown will not FIN/RST existing TCP connections (i.e., state ESTABLISHED).
-# Now, for the particular case of NeonVM, we just did 'pg_ctl stop'.
-# But, the libpagestore.c is currently not explicitly shutting down the TCP connection to pageservers, relying on the kernel
-# to implicitly close the socket on exit.
-# This sleep here is to give the kernel time to send the FIN/RST.
-sleep 1
 /neonvm/bin/poweroff
 `