Changes some aarch64 CIs g++ install & ubuntu ver.

GCS support was added to GCC in version 15, thus the rmake test for this
patch requires GCC15
Similarly, the ubuntu version is updated so the newer clang version is
available.

Author: CrooseGit

src/ci/docker/host-aarch64/aarch64-gnu-debug/Dockerfile

@@ -1,8 +1,8 @@
-FROM ubuntu:22.04
+FROM ubuntu:25.04
 
 ARG DEBIAN_FRONTEND=noninteractive
 RUN apt-get update && apt-get install -y --no-install-recommends \
-  g++ \
+  g++-15 \
   make \
   ninja-build \
   file \

src/ci/docker/host-aarch64/aarch64-gnu-llvm-20/Dockerfile

@@ -4,7 +4,7 @@ ARG DEBIAN_FRONTEND=noninteractive
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
   bzip2 \
-  g++ \
+  g++-15 \
   make \
   ninja-build \
   file \