[AIRFLOW-2591][AIRFLOW-2581] Set default value of autocommit to False in DbApiHook.run()
[AIRFLOW-2591][AIRFLOW-2581] Set default value of autocommit to False in DbApiHook.run()

In previous PR (AIRFLOW-2581), I changed the
default value  of
autocommit to True in DbApiHook.run(), which may
cause some performance
issues, so I changed it back to False.

Closes #3487 from imroc/AIRFLOW-2591

Acehaidrey/incubator-airflow,mtagle/airflow,mrkm4ntr/incubator-airflow,Fokko/incubator-airflow,airbnb/airflow,sergiohgz/incubator-airflow,owlabs/incubator-airflow,subodhchhabra/airflow,lyft/incubator-airflow,apache/airflow,malmiron/incubator-airflow,sergiohgz/incubator-airflow,edgarRd/incubator-airflow,r39132/airflow,r39132/airflow,dhuang/incubator-airflow,sekikn/incubator-airflow,bolkedebruin/airflow,sid88in/incubator-airflow,wileeam/airflow,fenglu-g/incubator-airflow,criccomini/airflow,r39132/airflow,wooga/airflow,DinoCow/airflow,artwr/airflow,subodhchhabra/airflow,apache/incubator-airflow,danielvdende/incubator-airflow,adamhaney/airflow,edgarRd/incubator-airflow,adamhaney/airflow,lxneng/incubator-airflow,spektom/incubator-airflow,nathanielvarona/airflow,fenglu-g/incubator-airflow,DinoCow/airflow,CloverHealth/airflow,lyft/incubator-airflow,lyft/incubator-airflow,nathanielvarona/airflow,apache/airflow,fenglu-g/incubator-airflow,nathanielvarona/airflow,wileeam/airflow,subodhchhabra/airflow,bolkedebruin/airflow,CloverHealth/airflow,criccomini/airflow,andyxhadji/incubator-airflow,airbnb/airflow,dhuang/incubator-airflow,artwr/airflow,edgarRd/incubator-airflow,cfei18/incubator-airflow,danielvdende/incubator-airflow,apache/incubator-airflow,akosel/incubator-airflow,Acehaidrey/incubator-airflow,Fokko/incubator-airflow,sid88in/incubator-airflow,Acehaidrey/incubator-airflow,gtoonstra/airflow,artwr/airflow,danielvdende/incubator-airflow,adamhaney/airflow,r39132/airflow,criccomini/airflow,owlabs/incubator-airflow,artwr/airflow,mistercrunch/airflow,lxneng/incubator-airflow,andyxhadji/incubator-airflow,sekikn/incubator-airflow,danielvdende/incubator-airflow,cfei18/incubator-airflow,adamhaney/airflow,malmiron/incubator-airflow,DinoCow/airflow,cfei18/incubator-airflow,jgao54/airflow,akosel/incubator-airflow,dhuang/incubator-airflow,nathanielvarona/airflow,sergiohgz/incubator-airflow,wooga/airflow,nathanielvarona/airflow,airbnb/airflow,fenglu-g/incubator-airflow,apache/airflow,andyxhadji/incubator-airflow,DinoCow/airflow,lxneng/incubator-airflow,cfei18/incubator-airflow,mistercrunch/airflow,malmiron/incubator-airflow,apache/airflow,jgao54/airflow,sid88in/incubator-airflow,sergiohgz/incubator-airflow,cfei18/incubator-airflow,subodhchhabra/airflow,nathanielvarona/airflow,spektom/incubator-airflow,spektom/incubator-airflow,cfei18/incubator-airflow,jgao54/airflow,mtagle/airflow,bolkedebruin/airflow,dhuang/incubator-airflow,lyft/incubator-airflow,mtagle/airflow,mtagle/airflow,spektom/incubator-airflow,mrkm4ntr/incubator-airflow,edgarRd/incubator-airflow,CloverHealth/airflow,bolkedebruin/airflow,jgao54/airflow,apache/incubator-airflow,bolkedebruin/airflow,wooga/airflow,Acehaidrey/incubator-airflow,andyxhadji/incubator-airflow,akosel/incubator-airflow,Fokko/incubator-airflow,Fokko/incubator-airflow,lxneng/incubator-airflow,wileeam/airflow,malmiron/incubator-airflow,mrkm4ntr/incubator-airflow,owlabs/incubator-airflow,akosel/incubator-airflow,mistercrunch/airflow,Acehaidrey/incubator-airflow,Acehaidrey/incubator-airflow,gtoonstra/airflow,sekikn/incubator-airflow,danielvdende/incubator-airflow,sekikn/incubator-airflow,sid88in/incubator-airflow,airbnb/airflow,apache/airflow,wileeam/airflow,criccomini/airflow,danielvdende/incubator-airflow,apache/airflow,mrkm4ntr/incubator-airflow,wooga/airflow,owlabs/incubator-airflow,mistercrunch/airflow,apache/incubator-airflow,gtoonstra/airflow,CloverHealth/airflow,gtoonstra/airflow