Fix generate-tarballs - exclude generated restdoc from license check
Fix generate-tarballs - exclude generated restdoc from license check

If we don't exclude `./generated` the `generate-tarballs` script
will fail when building UFS modules because of the license check
after compiling the codebase

pr-link: Alluxio/alluxio#9115
change-id: cid-c310f2698aacd5f0c48e265b1786ac870bc52944
Alluxio/alluxio,madanadit/alluxio,calvinjia/tachyon,bf8086/alluxio,Alluxio/alluxio,madanadit/alluxio,maobaolong/alluxio,maobaolong/alluxio,EvilMcJerkface/alluxio,Alluxio/alluxio,wwjiang007/alluxio,EvilMcJerkface/alluxio,wwjiang007/alluxio,maobaolong/alluxio,EvilMcJerkface/alluxio,maobaolong/alluxio,maobaolong/alluxio,calvinjia/tachyon,maobaolong/alluxio,bf8086/alluxio,Alluxio/alluxio,bf8086/alluxio,wwjiang007/alluxio,bf8086/alluxio,Alluxio/alluxio,madanadit/alluxio,wwjiang007/alluxio,madanadit/alluxio,wwjiang007/alluxio,calvinjia/tachyon,EvilMcJerkface/alluxio,wwjiang007/alluxio,madanadit/alluxio,Alluxio/alluxio,EvilMcJerkface/alluxio,calvinjia/tachyon,wwjiang007/alluxio,EvilMcJerkface/alluxio,calvinjia/tachyon,calvinjia/tachyon,Alluxio/alluxio,bf8086/alluxio,wwjiang007/alluxio,bf8086/alluxio,maobaolong/alluxio,Alluxio/alluxio,madanadit/alluxio,calvinjia/tachyon,EvilMcJerkface/alluxio,EvilMcJerkface/alluxio,madanadit/alluxio,maobaolong/alluxio,Alluxio/alluxio,maobaolong/alluxio,bf8086/alluxio,wwjiang007/alluxio,Alluxio/alluxio,madanadit/alluxio,wwjiang007/alluxio,calvinjia/tachyon,maobaolong/alluxio,bf8086/alluxio