go/oasis-node/txsource: Increase submission timeout

[kostko]

Sometimes it can take up to two minutes for a transaction to get included in a
block due to high load.

(This was masked before #3511 as submission was retried on all errors.)

[codecov]

Codecov Report

Merging #3568 (a595048) into master (3d6233c) will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #3568      +/-   ##
==========================================
- Coverage   66.61%   66.59%   -0.03%     
==========================================
  Files         377      377              
  Lines       34544    34544              
==========================================
- Hits        23013    23003      -10     
+ Misses       8229     8223       -6     
- Partials     3302     3318      +16     

Impacted Files	Coverage Δ
go/oasis-node/cmd/common/metrics/disk.go	65.38% <0.00%> (-19.24%)	⬇️
go/consensus/tendermint/api/api.go	74.66% <0.00%> (-10.67%)	⬇️
go/oasis-node/cmd/common/metrics/resource.go	78.94% <0.00%> (-10.53%)	⬇️
go/consensus/tendermint/epochtime/epochtime.go	86.20% <0.00%> (-6.90%)	⬇️
go/storage/mkvs/lookup.go	72.04% <0.00%> (-4.31%)	⬇️
go/consensus/tendermint/full/services.go	81.35% <0.00%> (-4.24%)	⬇️
go/storage/mkvs/remove.go	85.56% <0.00%> (-4.13%)	⬇️
...consensus/tendermint/apps/roothash/transactions.go	55.03% <0.00%> (-3.88%)	⬇️
go/runtime/tagindexer/tagindexer.go	66.27% <0.00%> (-2.33%)	⬇️
go/runtime/nodes/versioned.go	74.28% <0.00%> (-1.91%)	⬇️
... and 29 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 8737a18...a595048. Read the comment docs.