Overhaul core Tracker: add tests for `databases` mod #2432

Job	Run time
Formatting	15s
Build on ubuntu-latest (nightly)	3m 11s
Build on ubuntu-latest (stable)	3m 18s
Build on macos-latest (nightly)	4m 8s
Build on macos-latest (stable)	4m 10s
Build on windows-latest (nightly)	6m 28s
Build on windows-latest (stable)	8m 3s
Static Analysis (nightly)	1m 57s
Static Analysis (stable)	2m 1s
Units (nightly)	6m 21s
Units (stable)	6m 36s
E2E	0s
	46m 28s

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