[DL-9475] Updated the API documentation for the liabilities and payme…

[abutters]

…nts endpoints to include a description for the scenario that is simulated when an empty Gov-Test-Scenario header is supplied. The copyright year has also been updated in all of the source files.

[platops-pr-bot]

• SBT can be updated to 1.7.2 in project/build.properties
• uk.gov.hmrc.sbt-auto-build can be updated to 3.8.0 in project/plugins.sbt
• System property lookup can be removed in conf/application-json-logger.xml - Bootstrap's LoggerModule allows configuration of loggers without this. See README https://github.com/hmrc/bootstrap-play#version-5180
• Config key play.http.secret.key can be removed from conf/application.conf. This is already provided by Bootstrap
• Deprecated config uk.gov.hmrc.play.bootstrap.AuditModule can be changed to uk.gov.hmrc.play.audit.AuditModule in conf/application.conf