Consider dropping the support of sorting the vulnerabilities by report type

The following discussion from !76220 (merged) should be addressed:

• @minac started a discussion: (+2 comments)

  thought (non-blocking): Not related to this MR;

  I'm not sure if this will perform well so we might need to create a special functional index at some point.

  Also, not even sure if sorting by the report type is a commonly used and crucial functionality. /cc @thiagocsf, @matt_wilson