* [TD-3197] <fix>: fix taosdemo coverity scan issues.

* [TD-3197] <fix>: fix taosdemo coverity scan issue.

fix subscribeTest pids uninitialized.

* [TD-3197] <fix>: fix taosdemo coverity scan issues.

* [TD-3197] <fix>: fix coverity scan issues.

check super tbl info pointer.

* [TD-3197] <fix>: fix coverity scan issues.

move sub tbl query thread join into loop

* [TD-3197] <fix>: fix coverity scan issues.

remove unused variable

* [TD-3197] <fix>: fix coverity scan issues.

use more secure random library

* [TD-3197] <fix>: fix coverity scan issues.

use strncpy for more safe

* [TD-3197] <fix>: fix taosdemo coverity scan issue.

replace arc4random with rand().

* [TD-3197] <fix>: fix coverity scan issues.

check stb info pointer for start time

* [TD-3197] <fix>: fix coverity scan issues.

fix strcpy vulnerability

* [TD-3197] <fix>: fix taosdemo coverity scan issue.

modify taosdemoTest2. try to check database continously.
Co-authored-by: NShuduo Sang <sdsang@taosdata.com>