node: alternate implementation of grabbing node.ctx.Done() for #3919

[cce]

Summary

Based on conversation in #3919 a quick PR with small diff to demonstrate possible smaller change to fix the issue grabbing node.ctx.Done()

[codecov-commenter]

Codecov Report

Merging #3955 (7878d41) into master (704e0b4) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #3955      +/-   ##
==========================================
- Coverage   49.81%   49.79%   -0.02%     
==========================================
  Files         409      409              
  Lines       68929    68930       +1     
==========================================
- Hits        34335    34325      -10     
- Misses      30882    30899      +17     
+ Partials     3712     3706       -6     

Impacted Files	Coverage Δ
crypto/secp256k1/panic_cb.go	0.00% <ø> (ø)
crypto/secp256k1/scalar_mult_cgo.go	77.77% <ø> (ø)
crypto/secp256k1/secp256.go	42.25% <ø> (ø)
libgoal/lockedFileLinux.go	0.00% <ø> (ø)
libgoal/lockedFileUnix.go	0.00% <ø> (ø)
nodecontrol/kmdControl_common.go	0.00% <ø> (ø)
tools/network/dnssec/config_unix.go	72.72% <ø> (ø)
util/process_common.go	0.00% <ø> (ø)
util/util.go	0.00% <ø> (ø)
node/node.go	23.31% <100.00%> (-1.73%)	⬇️
... and 8 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 704e0b4...7878d41. Read the comment docs.