Use Java 17 as default to compile and run

[usmansaleem]

Use Java 17 as default to compile and run EthSigner code. EthSigner uses Besu's Metrics service as a dependency which is now compiled in Java 17 and cannot be used with EthSigner when later is compiled using Java 11.

Tasks:

Update gradle build file and update warning that Java 17 and upward can only be used for compilation
Remove jdk11 docker image and distDocker logic in gradle build file