go/runtime/client: use history for GetBlock(latest)

[ptrus]

Using history for all GetBlock requests prevents the case where the latest
block would already be available but not yet in history, leading to
inconsistent results compared to querying by specific block number.

[codecov]

Codecov Report

Merging #2795 into master will increase coverage by 0.15%.
The diff coverage is 77.77%.

@@            Coverage Diff             @@
##           master    #2795      +/-   ##
==========================================
+ Coverage   61.70%   61.86%   +0.15%     
==========================================
  Files         386      386              
  Lines       37131    37146      +15     
==========================================
+ Hits        22912    22980      +68     
+ Misses      11213    11117      -96     
- Partials     3006     3049      +43     

Impacted Files	Coverage Δ
go/runtime/history/history.go	73.58% <60.00%> (-1.42%)	⬇️
go/runtime/client/client.go	67.28% <100.00%> (-0.51%)	⬇️
go/runtime/client/tests/tester.go	100.00% <100.00%> (ø)
go/worker/compute/executor/committee/state.go	74.07% <0.00%> (-25.93%)	⬇️
go/worker/common/host/interface.go	38.46% <0.00%> (-15.39%)	⬇️
...ompute/txnscheduler/algorithm/batching/batching.go	78.66% <0.00%> (-6.67%)	⬇️
go/worker/compute/executor/committee/node.go	62.00% <0.00%> (-6.50%)	⬇️
go/consensus/api/grpc.go	59.30% <0.00%> (-4.66%)	⬇️
go/worker/storage/service_external.go	47.31% <0.00%> (-4.31%)	⬇️
go/worker/compute/txnscheduler/committee/node.go	62.34% <0.00%> (-4.02%)	⬇️
... and 22 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 327ce4b...ed4ceab. Read the comment docs.