go/worker/storage: Fix potential memory leak through context

[kostko]

See #4263

[codecov]

Codecov Report

Merging #4290 (68479ce) into master (6df3e80) will decrease coverage by 0.85%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #4290      +/-   ##
==========================================
- Coverage   69.37%   68.52%   -0.86%     
==========================================
  Files         411      411              
  Lines       47213    47215       +2     
==========================================
- Hits        32755    32352     -403     
- Misses      10475    10827     +352     
- Partials     3983     4036      +53     

Impacted Files	Coverage Δ
go/worker/storage/committee/node.go	78.57% <100.00%> (+0.05%)	⬆️
go/ias/http/http.go	20.33% <0.00%> (-44.07%)	⬇️
go/oasis-node/cmd/common/metrics/disk.go	65.51% <0.00%> (-20.69%)	⬇️
go/keymanager/api/policy_sgx.go	33.33% <0.00%> (-13.34%)	⬇️
go/runtime/host/sandbox/sandbox.go	67.03% <0.00%> (-12.09%)	⬇️
go/consensus/tendermint/apps/beacon/state/state.go	72.97% <0.00%> (-8.11%)	⬇️
go/oasis-node/cmd/common/metrics/resource.go	84.00% <0.00%> (-8.00%)	⬇️
go/consensus/tendermint/full/services.go	77.69% <0.00%> (-7.70%)	⬇️
...consensus/tendermint/apps/roothash/transactions.go	63.88% <0.00%> (-7.41%)	⬇️
go/oasis-node/cmd/ias/auth.go	68.96% <0.00%> (-6.90%)	⬇️
... and 42 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 6df3e80...68479ce. Read the comment docs.