ci: enable PGO on x86-64-v4

The GitHub Actions x86-64 runners are using ancient Azure instances
that lack AVX-512. As a result we can't run x86-64-v4 binaries.

We recently adopted custom runners. Let's see if they support
AVS-512 and enable PGO if they do.

Author: indygreg

ci-targets.yaml

@@ -218,13 +218,11 @@ linux:
       - "3.14"
     build_options:
       - debug
-      - noopt
-      - lto
+      - pgo+lto
     build_options_conditional:
       - options:
           - freethreaded+debug
-          - freethreaded+noopt
-          - freethreaded+lto
+          - freethreaded+pgo+lto
         minimum-python-version: "3.13"
 
   x86_64-unknown-linux-musl: