Remove the periodic Centos 8 job

Centos 9 fips tests are already merged on Nova and Centos 8 jobs were already replaced by Centos 9,
this patch will delete a Centos 8 periodic pipeline that should have been deleted on previous patcc.

Change-Id: Ib735e9b52915639006bb08424d83f8ee39113d4f

Author: afaranha

.zuul.yaml

@@ -781,7 +781,3 @@
         - nova-emulation
         - tempest-integrated-compute-centos-9-stream:
             irrelevant-files: *nova-base-irrelevant-files
-    periodic:
-      jobs:
-        - tempest-centos8-stream-fips:
-            branches: master