Fix javadoc encoding

[chenjunjiedada]

The PR set the javadoc task encoding option since the build task fails on the system that uses ascii. For example, we can reproduce the issue when setting javadoc encoding to ASCII.

> Task :iceberg-orc:javadoc FAILED                                                                                                                         
/home/cjj/iceberg/orc/src/main/java/org/apache/iceberg/orc/ORCSchemaUtil.java:233: error: unmappable character for encoding ASCII                          
   * which would then use its schema evolution to map that to the writer??????s schema.                                                                       
                                                                        ^                                                                                  
/home/cjj/iceberg/orc/src/main/java/org/apache/iceberg/orc/ORCSchemaUtil.java:233: error: unmappable character for encoding ASCII                          
   * which would then use its schema evolution to map that to the writer??????s schema.                                                                       
                                                                         ^                                                                                 
/home/cjj/iceberg/orc/src/main/java/org/apache/iceberg/orc/ORCSchemaUtil.java:233: error: unmappable character for encoding ASCII                          
   * which would then use its schema evolution to map that to the writer??????s schema.  

I don't update the quote character here, it should be updated, though.

[kbendick]

This is a great catch. Thanks for taking care of this @chenjunjiedada.

[rdblue]

Thanks, @chenjunjiedada. I agree, this should be UTF-8.