* Reuse connection for test data loading & JDBC data loading overhaul

* Revert silly change

* Remove unneeded logic for recording which datasets are loaded or not-yet-loaded

* Ok so I guess we do need the code to detect duplicate dataset loading after all

* B I G  improvements

* Appease Kondo

* Test fixes 

* More test fixes 

* Fix dataset-already-loaded?-test

* Fix test

* Fix Presto JDBC and greatly improve test data load speed for it

* Postgres test fix 

* Fix compilation errors

* MySQL fixes 

* Fix syntax error

* MySQL fixes 

* Implement `dataset-already-loaded?` for Athena and cache the set of existing databases

* Fix Redshift

* Fix Presto JDBC

* Vertica test fix 

* Fix Oracle dataset-already-loaded?

* Test fixes and parallelize some API tests.

* Test fixes 

* Oracle test fix? 

* Another test fix 

* Stop putting random spaces in code bodies this is not JavaScript code

* with-temp-vals-in-db should merge in original value of Database settings

* The most test fixes 

* 3 or 4 test fixes 

* Add schemas around stuff to catch errors

* Appease Kondo

* Implement dataset-already-loaded? for vertica

* Implement dataset-already-loaded? for SQLite and Snowflake

* Redshift: drop session schema when test suite finishes [ci skip]

* Update Hawk version

* PR feedback

* Bump Hawk version

* Skip after-run for drivers that don't have test extensions

---------

Co-authored-by: Cal Herries <39073188+calherries@users.noreply.github.com>

Upgrade Liquibase to latest version; remove final Java source file and need for `clojure -X:deps prep` (#20611)

* Upgrade Liquibase to latest version

* Try adjusting log

* Fix checksums for the TWO migrations with ID = 32

* FINALLY get Liquibase to use Log4j2

* Set Liquibase ConsoleUIService OutputStream to null OutputStream

* Manually define a package for our H2 proxy class so Java 8 works

* Fix package-name determination code

* Update migrations file spec

* `databasechangelog` shouldn't be upper-case

* Lower-case quartz table names

* More MySQL fixes 

* Properties for all the Quartz tables 

* Formatting tweaks [ci skip]

* Revert a few more busted changes

* Fix more busted changes

* Bump Liquibase version to 4.8.0 to fix MySQL defaultValueBoolean bug

* OMG I think I finally fixed MySQL

* Remove Java source file and prep-deps code

* Remove two more references to bin/prep.sh

* Minor cleanup

* Revert unneeded changes

* Fix busted indentation

* Don't search inside java/ anymore since it's G-O-N-E

* Appease the namespace linter

* Update src/metabase/db/liquibase/h2.clj

* Fix logging utils

* Test fixes