Fixed Issues in Livy

Review the list of Livy issues that are resolved in Cloudera Runtime 7.2.15.

CDPD-19276: The HTTP headers Strict-Transport-Security (HSTS) and Content-Security-Policy (CSP) are populated in Livy and Livy for Spark 3 by default and their values can be customized via a configuration setting.

This issue is now resolved.