ticlient: set max send/recv msg size match tikv's config

[lysu]

What problem does this PR solve?

Now TiDB and TiKV use different max send/recv msg limit:

DB:

tidb/store/tikv/client.go

Line 56 in 9b4940b

var MaxSendMsgSize = 1<<31 - 1

KV:

https://github.com/tikv/tikv/blob/8dae71abe25cdcc511116f7d5b29312dffc2b152/src/server/server.rs#L108

What is changed and how it works?

set TiDB's send to 10M and recv to ulimited(MaxInt)

Check List

Tests

• Unit test
• Integration test

Code changes

• N/A

Side effects

• N/A

Related changes

• Need to cherry-pick to the release branch

---

This change is 

[lysu]

/run-all-tests

[codecov]

Codecov Report

Merging #10706 into master will decrease coverage by 0.0351%.
The diff coverage is 100%.

@@               Coverage Diff                @@
##             master     #10706        +/-   ##
================================================
- Coverage   79.6786%   79.6434%   -0.0352%     
================================================
  Files           414        414                
  Lines         87696      87731        +35     
================================================
- Hits          69875      69872         -3     
- Misses        12647      12684        +37     
- Partials       5174       5175         +1

[zz-jason]

LGTM

[zz-jason]

A better way is to use a common config on these values for tidb and tikv.

[jackysp]

LGTM