Rename rockylinux9 build directory to rocky9

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

alpine3.24/Dockerfile

@@ -335,7 +335,7 @@ RUN curl --fail --location --output numactl.tar.gz \
 # folly/debugging/symbolizer/Elf.cpp). Patching around each one as it
 # surfaces is more likely to introduce subtle bugs than to reach a solid
 # build, so this stack is not built here. See INCLUDED_LIBRARIES.md for
-# details; debian13 and rockylinux9 are unaffected and still build it.
+# details; debian13 and rocky9 are unaffected and still build it.
 
 RUN curl --fail --location --output util-linux.tar.xz \
         https://mirrors.edge.kernel.org/pub/linux/utils/util-linux/v2.42/util-linux-2.42.2.tar.xz \