[Chapel Merge] Pin CentOS 9 to use LLVM 19

Branch: refs/heads/main
Revision: 8bc2e99978f9a9529720ab5c63ce8f0638de698b
Author: benharsh
Link: Pin CentOS 9 to use LLVM 19 by benharsh · Pull Request #28775 · chapel-lang/chapel · GitHub
Log Message:
Pin CentOS 9 to use LLVM 19 (#28775)

The EPEL offerings for centos 9 and 10 have somewhat diverged, with 10
supporting clang20 but 9 only having clang19.

Trivial, not reviewed.

Compare: Comparing ed33d7db8f4a3fe4f19d6f0b320acf4e21d04f3c...69f6c2d9a82d0bab21f381fce9ebc32ba761a3ca · chapel-lang/chapel · GitHub

Diff:
M util/devel/test/portability/apptainer/current/centos-stream-9/image.def
https://github.com/chapel-lang/chapel/pull/28775.diff