Chore: Update test database initialization (#81673)

* streamline initialization of test databases, support on-disk sqlite test db

* clean up test databases

* introduce testsuite helper

* use testsuite everywhere we use a test db

* update documentation

* improve error handling

* disable entity integration test until we can figure out locking error

pkg/tests/testsuite/testsuite.go

@@ -0,0 +1,15 @@
+package testsuite
+
+import (
+	"os"
+	"testing"
+
+	"github.com/grafana/grafana/pkg/infra/db"
+)
+
+func Run(m *testing.M) {
+	db.SetupTestDB()
+	code := m.Run()
+	db.CleanupTestDB()
+	os.Exit(code)
+}