Ledger: Close the ledger at node shutdown

[algonautshant]

The ledger is never closed. This closes the ledger when shutting down the node.

[codecov]

Codecov Report

Merging #5668 (06d9cba) into master (3425e85) will increase coverage by 0.02%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #5668      +/-   ##
==========================================
+ Coverage   55.15%   55.17%   +0.02%     
==========================================
  Files         465      465              
  Lines       65024    65025       +1     
==========================================
+ Hits        35862    35877      +15     
+ Misses      26769    26759      -10     
+ Partials     2393     2389       -4     

Files Changed	Coverage Δ
node/node.go	4.14% <0.00%> (-0.01%)	⬇️

... and 12 files with indirect coverage changes

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[bbroder-algo]

seems pretty innocuous, although ledger.Close() does kick off a lot of previously unexecuted locks and waits. but closing releases a lot of resources and was probably part the original lifecycle design.