enh: optimize the error code when create and drop a db in dropping status

* fix: add installation folder to system path

* fix: add c:\tdengine in env path to issc setup

fix(shell): adjust show result format

docs: add examples of case expressions

test: modify case delete_data.py to three test cases

fix: fix error handling for query msg preprocessing

perf: optimize sma calculation

enh(tdb): new interface of meta prep async commit

docs: set monitor default value

fix(query): add mode with selectivity rows

refactor: refactor to avoid spin operator in exchange operator.

reafct: adjust sync propose

release: build 3.0.1.6 (merge from main to 3.0)

docs: add case expressions

test：modify testcase that reduce numbers of db and  repetitions

fix: avoid cpu load imbalance 

refact: adjust sync log

refactor(sync): delete assert, add error log