Currently failures to compile a script usually lead to a ScriptException, which
inherits the 500 INTERNAL_SERVER_ERROR from ElasticsearchException if it does
not contain another root cause. Instead, this should be a 400 Bad Request error.
This PR changes this more generally for script compilation errors by changing
ScriptException to return 400 (bad request) as status code.
Closes#12315
The getDate() and getDates() existed prior to 5.x on long fields in
scripting. In 5.x, a new Date type for ScriptDocValues was added. The
getDate() and getDates() methods were left on long fields and added to date
fields to ease the transition. This commit removes those methods for
7.0.