IMPALA-9999's upgrade of flatbuffers to 1.12 causes a conflict with Hive

IMPALA-9999's upgrade to GCC 10.4 switched to flatbuffers 1.12 as older flatbuffers versions do not compile on newer GCC versions. This required switching the Java version as well. However, upgrading the Java version causes a conflict with Hive, which uses flatbuffers 1.9.

Since Impala is upgrading in order to avoid the C++ compilation issue, we can resolve the conflict by using flatbuffers 1.9 and patching it with the fix from here: https://github.com/google/flatbuffers/commit/86153fd7405ad3bae28aee7f5affdbeb2d77e533