Bring back reset db explicitly called at CI entry

[potiuk]

---

Issue link: WILL BE INSERTED BY boring-cyborg

Make sure to mark the boxes below before creating PR: [x]

• Description above provides context of the change
• Unit tests coverage for changes (not needed for documentation changes)
• Commits follow "How to write a good git commit message"
• Relevant documentation is updated including usage instructions.
• I will engage committers as explained in Contribution Workflow Example.

---

In case of fundamental code change, Airflow Improvement Proposal (AIP) is needed.
In case of a new dependency, check compliance with the ASF 3rd Party License Policy.
In case of backwards incompatible changes please leave a note in UPDATING.md.
Read the Pull Request Guidelines for more information.

[kaxil]

CI fails with this update for v1-10-test:

https://travis-ci.org/github/apache/airflow/jobs/665238808

[codecov-io]

Codecov Report

Merging #7798 into master will increase coverage by 21.63%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           master    #7798       +/-   ##
===========================================
+ Coverage   65.25%   86.89%   +21.63%     
===========================================
  Files         923      924        +1     
  Lines       44661    44674       +13     
===========================================
+ Hits        29144    38818     +9674     
+ Misses      15517     5856     -9661     

Impacted Files	Coverage Δ
airflow/bin/airflow	84.61% <0.00%> (ø)
airflow/providers/google/cloud/operators/vision.py	99.63% <0.00%> (+0.36%)	⬆️
...osoft/azure/operators/azure_container_instances.py	78.14% <0.00%> (+0.66%)	⬆️
airflow/utils/db.py	98.31% <0.00%> (+0.84%)	⬆️
airflow/providers/postgres/hooks/postgres.py	94.36% <0.00%> (+1.40%)	⬆️
...rflow/providers/databricks/operators/databricks.py	92.24% <0.00%> (+1.72%)	⬆️
airflow/bin/cli.py	94.79% <0.00%> (+2.08%)	⬆️
.../providers/google/cloud/operators/presto_to_gcs.py	38.66% <0.00%> (+2.66%)	⬆️
airflow/models/log.py	100.00% <0.00%> (+3.03%)	⬆️
airflow/executors/celery_executor.py	88.51% <0.00%> (+3.37%)	⬆️
... and 488 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6ec51b3...cb1d4cc. Read the comment docs.