tikv: invalidate store's regions when store be removed in kv

[lysu]

What problem does this PR solve?

this question can be reproduced by TestReplaceAddrWithNewStore testcase:

1. access A store using region1, then region1 will be put into region-cache
2. remove A store(store_id=1) in ip1:port2 from kv-cluster
3. then add B store(store_id=2) in the same ip1:port2 into kv-cluster
4. access region1 again via region cache(make sure TTL isn't expired)

make sure 2-3 no any request hit region1, then 4 will be fail in infline loop

the root reason is: region-cache will try async fetch store A's new address but got nil, region request will keep retry and wait "new addr", this also will make cache TTL have no chance to invalidate cached info.

What is changed and how it works?

invalidate regions in removed store, to let request have the chance to reload new region's store info from pd.

after this modification, TestReplaceAddrWithNewStore can works

Check List

Tests

• Unit test

Code changes

• invalidate code

Side effects

• N/A

Related changes

• Need to cherry-pick to the release 3.0

---

This change is 

[lysu]

/run-all-tests

[lysu]

/run-unit-test

[codecov]

Codecov Report

Merging #11567 into master will decrease coverage by 0.2811%.
The diff coverage is 100%.

@@               Coverage Diff                @@
##             master     #11567        +/-   ##
================================================
- Coverage   81.4916%   81.2105%   -0.2812%     
================================================
  Files           427        426         -1     
  Lines         93196      91828      -1368     
================================================
- Hits          75947      74574      -1373     
- Misses        11862      11889        +27     
+ Partials       5387       5365        -22

[lysu]

@coocood @tiancaiamao PTAL thx

[coocood]

LGTM

[jackysp]

LGTM

[sre-bot]

/run-all-tests

[sre-bot]

cherry pick to release-3.0 failed

[dikang123]

Does this issue affect tidb v2.1.15？

[lysu]

@dikang123 no, this issue only affect v3.0.0 and v3.0.1