[Improvement] Backend storage repeatedly restarts in a UT class.

[mchades]

What would you like to be improved?

in the test class, each UT will restart H2, MySQL, and PostgreSQL, which is unnecessary but also causes tests to slow since they need to start and stop the container repeatedly.

gravitino/core/src/test/java/org/apache/gravitino/storage/TestEntityStorage.java

Lines 116 to 123 in fb3d900

	static Object[] storageProvider() {
	return new Object[] {"h2", "mysql", "postgresql"};
	}
	@AfterEach
	void closeSuit() throws IOException {
	ContainerSuite.getInstance().close();
	}

How should we improve?

reuse the backend storage instance in the class