Update configuration metadata appendix to remove description for Gradle 4.5 and earlier as it is no longer supported #23245
Description
The reference documentation describes how to configuration the annotation processor to generate configuration property metadata. For Gradle, different configuration for Gradle 4.5 and earlier and Gradle 4.6 and later is described. The minimum supported version of Gradle is 4.10 so the description can be simplified to only describe the Gradle 4.6 and later approach.