Contains Spiral patches:
- Spiral Patch 007: 007_mariadb-10.2.0.partition_fulltext.diff  MDEV-7705
- Spiral Patch 038: 038_mariadb-10.2.0.partition_fulltext2.diff MDEV-7734

- This commit has the following differences compared to the original patches:
  - Added necessary full text search cleanup at the storage engine layer
    that was omitted in the original patch.
  - Added test case.