Small fix to help prevent falsely reporting clock skew when the

DB is under heavy load.

There is a semantic difference between how `NOW()` and `SYSDATE()` work
([docs](https://dev.mysql.com/doc/refman/8.4/en/date-and-time-functions.html#function_sysdate)),
mainly being that `NOW()` captures the time when the query begins
execution and can be manipulated by some variables (generally for
testing purposes) while `SYSDATE()` returns the time the function is
executed (i.e. closer to when it is returned to the client) and cannot
be manipulated.

GitOrigin-RevId: 298fb59bc79e5f6b3fed96017bd2cdd2f7a6b279

Author: mpeyper

misk-hibernate/src/main/kotlin/misk/hibernate/HibernateHealthCheck.kt

@@ -29,7 +29,7 @@ internal class HibernateHealthCheck(
     val databaseInstant = try {
       val sessionFactory = sessionFactoryService.get().sessionFactory
       sessionFactory.openSession().use { session ->
-        session.createNativeQuery("SELECT NOW()").uniqueResult() as Timestamp
+        session.createNativeQuery("SELECT SYSDATE()").uniqueResult() as Timestamp
       }.toInstant()
     } catch (e: Exception) {
       logger.error(e) { "error performing hibernate health check" }