stats: fix unstable test

[alivxxx]

What problem does this PR solve?

FAIL: dump_test.go:26: testStatsSuite.TestConversion
dump_test.go:49:
    assertTableEqual(c, loadTbl, tbl)
handle_test.go:100:
    c.Assert(a.Count, Equals, b.Count)
... obtained int64 = 9
... expected int64 = 3

What is changed and how it works?

Since #10771, there will be a background goroutine to Update even if stats-lease is 0, yet some tests are still under the assumption of no automatic updates. In TestConversion, the explicit Update and background Update may conflict each other, since their read and cache updates are two separate operations, so there may be the chances that the newer updates are overwritten by the older updates.

This PR fixes it by disabling the background goroutine by set the stats-lease to negative.

Also, there are still chances that the wrong result is caused by the failure of some stats operations, but there are no error checks for them, so this PR also checks the error for them.

Check List

Tests

• Unit test

Code changes

• Has exported function/method change

Side effects

• None

Related changes

• None

[codecov]

Codecov Report

Merging #10953 into master will not change coverage.
The diff coverage is n/a.

@@             Coverage Diff             @@
##             master     #10953   +/-   ##
===========================================
  Coverage   80.9319%   80.9319%           
===========================================
  Files           418        418           
  Lines         89275      89275           
===========================================
  Hits          72252      72252           
  Misses        11789      11789           
  Partials       5234       5234

[coocood]

LGTM

[winoros]

lgtm

[alivxxx]

/run-all-tests