TRUNK-6208: Fix null config directory path in DeleteDomainChecksumsChangeset.

[k4pran]

Fix NPE issue originating from DeleteDomainChecksumsChangeset. See openmrs/openmrs-core#4637 (comment)

ERROR - Slf4JLogger.log(39) |2024-05-27T01:05:29,953| ChangeSet liquibase.xml::delete-concepts-checksums-20211025::iniz encountered an exception.
java.lang.NullPointerException: null
	at java.base/java.util.Objects.requireNonNull(Objects.java:209) ~[?:?]
	at java.base/sun.nio.fs.UnixFileSystem.getPath(UnixFileSystem.java:263) ~[?:?]
	at java.base/java.nio.file.Path.of(Path.java:147) ~[?:?]
	at java.base/java.nio.file.Paths.get(Paths.java:69) ~[?:?]
	at org.openmrs.module.initializer.api.ConfigDirUtil.<init>(ConfigDirUtil.java:72) ~[initializer-api-2.6.0.jar:?]
	at org.openmrs.module.initializer.api.ConfigDirUtil.<init>(ConfigDirUtil.java:81) ~[initializer-api-2.6.0.jar:?]
	at org.openmrs.module.initializer.liquibase.DeleteDomainChecksumsChangeset.execute(DeleteDomainChecksumsChangeset.java:52) ~

I did duplicate some code from InitializerServiceImpl as it didn't seem there was an easy way to autowire into liquibase customChange classes.

[mks-d]

Thanks @k4pran and @dkayiwa 🙏