cidb: use sqlalchemy.engine.url.URL instead of connection string
cidb: use sqlalchemy.engine.url.URL instead of connection string

Using the URL class allows special characters in the db connection
password to be quoted correctly, in older versions of sqlalchemy. This
allows the cidb_integration_test.py to pass outside of the chroot.

BUG=chromium:387755
TEST=cidb_integration_test.py

Change-Id: I85b5284f026c53a716b56a77c59acb24c177c979
Reviewed-on: https://chromium-review.googlesource.com/209012
Tested-by: Aviv Keshet <178e8ae417efbe404feca7ab4cb8f0ba8c109369@chromium.org>
Reviewed-by: Yu-Ju Hong <52dc720c411f8e2156e608c1a8b894a917489667@chromium.org>
Commit-Queue: Aviv Keshet <178e8ae417efbe404feca7ab4cb8f0ba8c109369@chromium.org>

bpsinc-native/src_third_party_chromite,bpsinc-native/src_third_party_chromite,bpsinc-native/src_third_party_chromite