Remove support for combining SARIF runs with non-unique categories #4446

Job	Run time
Config export (ubuntu-latest, nightly-latest)	1m 2s
Config export (windows-latest, nightly-latest)	3m 4s
Config export (macos-latest, nightly-latest)	1m 31s
Config export (macos-latest, linked)	57s
Config export (ubuntu-latest, linked)	1m 1s
Config export (windows-latest, linked)	3m 0s
	10m 35s

Provide feedback