[to #250] cdc: remove empty value check in client-go

[pingyu]

Signed-off-by: pingyu [email protected]

What problem does this PR solve?

Issue Number: close #250

Problem Description: cdc: changefeed raise error "empty value is not supported"

What is changed and how does it work?

• Remove empty value check in tikv/client-go. See rawkv: permit empty value client-go#612 (It's a temporarily fix on personal fork. Will pull to master later)
• Modify integration test to generate test data with empty value
• Prolong sleep duration of "move_keyspan" test, as the original "5s" seems to be not enough. See here.

Code changes

Check List for Tests

This PR has been tested by at least one of the following methods:

• Integration test

Side effects

• No side effects

Related changes

• No related changes

[codecov]

Codecov Report

Merging #277 (fda2409) into main (f781076) will increase coverage by 0.2472%.
The diff coverage is n/a.

Additional details and impacted files

@@               Coverage Diff                @@
##               main       #277        +/-   ##
================================================
+ Coverage   54.3283%   54.5755%   +0.2471%     
================================================
  Files           238        238                
  Lines         20227      20227                
================================================
+ Hits          10989      11039        +50     
+ Misses         8358       8289        -69     
- Partials        880        899        +19     

Flag	Coverage Δ		*Carryforward flag
br	39.5359% <ø> (ø)		Carriedforward from ff24bb8
cdc	61.5034% <ø> (+0.3610%)	⬆️

*This pull request uses carry forward flags. Click here to find out more.

Impacted Files	Coverage Δ
cdc/cdc/kv/region_worker.go	78.7500% <0.0000%> (-0.8334%)	⬇️
cdc/cdc/sorter/unified/unified_sorter.go	91.6666% <0.0000%> (-0.6945%)	⬇️
cdc/cdc/sorter/unified/merger.go	69.5792% <0.0000%> (ø)
cdc/cdc/kv/client.go	84.7262% <0.0000%> (+0.7204%)	⬆️
cdc/pkg/orchestrator/etcd_worker.go	80.2521% <0.0000%> (+1.6806%)	⬆️
cdc/cdc/sorter/unified/file_backend.go	53.9473% <0.0000%> (+20.1754%)	⬆️

[zeminzhou]

LGTM～

[haojinming]

LGTM