Disable identifier filter when group has more than 20k vulnerabilities

The following discussion from !179363 (merged) should be addressed:

• @svedova started a discussion: (+1 comment)

  FYI, if the group has more than 20k this feature won't work. Right now the behaviour is that the autocomplete won't work and GraphQL will return an error.

  I suggest disabling this filter (grey it out) with a popover that clarifies why it's disabled. @wandering_person how hard it is to inject the total amount of variables on the page load for a given/project?