[TD-4422]-adding test cases for different combination of drop, child_table_exist, and auto_create_table

commit 0c81e3c0ba89c86f6d17d51d5056146e177cace5
Author: Huo Linhe <linhehuo@gmail.com>
Date:   Fri May 14 10:27:13 2021 +0800

    [TD-4160]<fix>: remove python connector soft links, fix tests and documents

commit f439fce413423e7d7c97eef180c93d63dedab32e
Author: Huo Linhe <linhehuo@gmail.com>
Date:   Wed May 12 18:50:53 2021 +0800

    [TD-182]: bump python connector version to v2.0.10 (#6091)

    Also fix url error in setup.py

commit 4ae55d494a262e482f6b34e8bf193cc6af62a886
Author: Huo Linhe <linhehuo@gmail.com>
Date:   Wed May 12 09:49:26 2021 +0800

    [TD-4370]<fix>: merge python connector changes to master

    Inludes:

    [TD-182]<enhance>: use single repo for python connector (#6036)

    * [TD-182]<enhance>: use single repo for python connector

    Remove code for each platform and build up one single python code base
    for windows/osx/linux platforms and python2/python3 runtime.

    * [TD-182]<enhance>: remove redundant code in python connector

    * [TD-4149] <fix>: fix python connection config error

* [TD-4136]<fix>: taosdemo max records per req < 32767

* [TD-4136]<fix>: taosdemo check insert rows not more than 32767.

check insert rows for progressive.

* fix with answer_yes.
Co-authored-by: NShuduo Sang <sdsang@taosdata.com>

Co-authored-by: NShuduo Sang <sdsang@taosdata.com>

[TD-4037]<test>: add taodemo-testcase that childtable_count is less than or equal zero and num_of_records_per_req  is  equal zero

By this commit, It will close TD-3639.

It will not require test case to write *correct* datetime string to pass
a test case. One test could use seconds, milliseconds or microseconds to
check data.

That means the three tests are equivalent:

```python
.checkData(0, 0, "2020-01-01 00:00:00")
.checkData(0, 0, "2020-01-01 00:00:00.000")
.checkData(0, 0, "2020-01-01 00:00:00.000000")
```
Co-authored-by: NHuo Linhe <linhehuo@gmail.com>

* [TD-4032]Eliminate false alarms

* update rules

* [TD-4025]<fix>: travis ci broken due to valgrind dependency missed.

* [TD-4025]<fix>: travis ci broken due to valgrind dependency missed.

change focal to bionic.

* [TD-4025]<fix>: travis ci broken due to valgrind dependency missed.

install python3.8

* [TD-4025]<fix>: travis ci broken due to valgrind dependency missed.

install python3.8 and pip, setuptools

* [TD-4025]<fix>: travis ci broken due to valgrind dependency missed.

install python3.8, and install pip and setuptools

* [TD-4025]<fix>: travis ci broken due to valgrind dependency missed.

modify smoketest.sh to python3.8
Co-authored-by: NShuduo Sang <sdsang@taosdata.com>

Refactored crash_gen to have the TdeSubProcess own the SvcMgrThread object, also switched to Pylance