infoschema: fix load drop database schema bug and refine db-table api error.

[crazycs520]

What problem does this PR solve?

• Fix dirty table info in infoSchema.sortedTablesBuckets after drop database.
• curl http://$IP:10080/db-table/{table_id} should return error when we cann't find the database info.

drop database if exists test;
create database if not exists test;
use test;
create table t1 (a int);
create table t2 (a int);  -- suppose table id of t2 is 48.  
create table t3 (a int);
drop database if exists test;

▶ curl "http://$IP:10080/db-table/48"
{
 "db_info": null,       # here is the problem. The `test` database was already droped.
 "table_info": {        # but we can still get the table t2 info.
  "id": 48,
  "name": {
   "O": "t2",
   "L": "t2"
  },
.
.
.

What is changed and how it works?

Fix bug of applyDropSchema function.

Check List

Tests

• Unit test

Code changes

• Has exported function/method change

Side effects

Related changes

• Need to cherry-pick to the release branch

[codecov]

Codecov Report

Merging #11573 into master will not change coverage.
The diff coverage is n/a.

@@             Coverage Diff             @@
##             master     #11573   +/-   ##
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  Coverage   81.2163%   81.2163%           
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  Files           426        426           
  Lines         91846      91846           
===========================================
  Hits          74594      74594           
  Misses        11887      11887           
  Partials       5365       5365

[zimulala]

LGTM

[crazycs520]

/run-all-tests

[winkyao]

LGTM

[bb7133]

LGTM

[sre-bot]

cherry pick to release-2.1 failed

[sre-bot]

cherry pick to release-3.0 failed