Run mvn clean in CI

[asfimport]

Currently parquet-mr CI does not run mvn clean, modules without changes are not recompiled each time.

Reporter: Qinghui Xu / @qinghui-xu Assignee: Qinghui Xu / @qinghui-xu

Related issues:

• Invoke mvn clean in Travis (is duplicated by)

_{Note: This issue was originally created as PARQUET-1900. Please see the migration documentation for further details.}