DRILL-5990: Drill should not startup with JRE sourced java executable
Currently, the check for the Java compiler is made only during query execution.
This commit ensures that if the java executable used for instantiating the Drillbit is from a JRE (i.e. the Java compiler is not available), the Drillbit will fail with the exception reported in the logs:
```
Exception in thread "main" org.apache.drill.exec.exception.DrillbitStartupException: JDK Java compiler not available. Ensure Drill is running with the java executable from a JDK and not a JRE
at org.apache.drill.exec.server.Drillbit.<init>(Drillbit.java:138)
at org.apache.drill.exec.server.Drillbit.start(Drillbit.java:409)
at org.apache.drill.exec.server.Drillbit.start(Drillbit.java:389)
at org.apache.drill.exec.server.Drillbit.main(Drillbit.java:385)
```
