Remove unused hikari config from application properties

[mpgxvii]

• Getting an error: java.lang.IllegalStateException: The configuration of the pool is sealed once started. Use HikariConfigMXBean for runtime changes.
• I think these were not used and tested for a while (in previous releases) and was used in the latest release (which resulted in the error), but if this is needed, we would need a custom implementation of the HikariConfig