infoschema,store: change leader weight/score type to float64

[cyliu0]

What problem does this PR solve?

Leader weight/score types are incompatible with PD, introduced by #10248
Fix #12062

What is changed and how it works?

Change leader weight/score type to float64

Check List

Tests

• Unit test
• Manual test (add detailed scripts or steps below)

$ pd-ctl -u http://127.0.0.1:2379 store weight 1 999978974.837482 999978974.837482
Success!

mysql> select * from information_schema.tikv_store_status\G
*************************** 1. row ***************************
         STORE_ID: 1
          ADDRESS: 127.0.0.1:20160
      STORE_STATE: 0
 STORE_STATE_NAME: Up
            LABEL: null
          VERSION: 4.0.0-alpha
         CAPACITY: 234 GiB
        AVAILABLE: 57 GiB
     LEADER_COUNT: 20
    LEADER_WEIGHT: 999978974.837482
     LEADER_SCORE: 0.000000020000420512091697
      LEADER_SIZE: 20
     REGION_COUNT: 20
    REGION_WEIGHT: 999978974.837482
     REGION_SCORE: 0.8436756740337913
      REGION_SIZE: 20
         START_TS: 2019-09-11 11:35:25
LAST_HEARTBEAT_TS: 2019-09-11 11:41:05
           UPTIME: 5m40.804486s
1 row in set (0.01 sec)

Code changes

• Has exported function/method change

Related changes

• Need to cherry-pick to the release branch

Release note

• Fix leader weight/score types are incompatible with PD

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #12151 into master will not change coverage.
The diff coverage is n/a.

@@             Coverage Diff             @@
##             master     #12151   +/-   ##
===========================================
  Coverage   81.3152%   81.3152%           
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  Files           452        452           
  Lines         96742      96742           
===========================================
  Hits          78666      78666           
  Misses        12440      12440           
  Partials       5636       5636

[alivxxx]

LGTM

[zz-jason]

LGTM

[sre-bot]

Your auto merge job has been accepted, waiting for 12149

[sre-bot]

/run-all-tests