Vulnerability Management DDL to replace raw JSON in the DB
DRI: @Quintasan
Issue board: https://gitlab.com/gitlab-org/gitlab/-/boards/9673608?epic_id=97511
Based on the discussion in https://gitlab.com/gitlab-com/content-sites/handbook/-/issues/498#note_2601856489 we will proceed with the removal of `vulnerability_occurrences.raw_metadata` column
This should save us 190 GB of space
```
gitlabhq_dblab> select
pg_size_pretty(sum(pg_column_size(raw_metadata))) as total_size,
pg_size_pretty(avg(pg_column_size(raw_metadata))) as average_size,
sum(pg_column_size(raw_metadata)) * 100.0 / pg_total_relation_size('vulnerability_occurrences') as percentage
from vulnerability_occurrences;
+------------+-----------------------------+---------------------+
| total_size | average_size | percentage |
|------------+-----------------------------+---------------------|
| 190 GB | 1268.2885333422742607 bytes | 46.6889158373493485 |
+------------+-----------------------------+---------------------+
```
[See Design Issue](https://gitlab.com/gitlab-org/gitlab/-/issues/231287).
epic