Dont run the self-hosted workflows when not available

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from #23678)

(cherry picked from commit 74fd682)

.github/workflows/ci.yml

@@ -93,6 +93,7 @@ jobs:
       run: make test HARNESS_JOBS=${HARNESS_JOBS:-4}
 
   self-hosted:
+    if: github.repository == 'openssl/openssl'
     strategy:
       matrix:
         os: [freebsd-13.2, ubuntu-arm64-22.04]