Update gcc leg from v14 to v15

docs/workflow/using-docker.md

@@ -47,7 +47,7 @@ The main Docker images are the most commonly used ones, and the ones you will pr
 | Azure Linux (x64) | Debian sid                 | LoongArch     | `mcr.microsoft.com/dotnet-buildtools/prereqs:azurelinux-3.0-net10.0-cross-loongarch64`   | `/crossrootfs/loongarch64` |
 | Azure Linux (x64) | Ubuntu 18.04               | S390x         | `mcr.microsoft.com/dotnet-buildtools/prereqs:azurelinux-3.0-net10.0-cross-s390x`         | `/crossrootfs/s390x`   |
 | Azure Linux (x64) | Ubuntu 18.04 (Wasm)        | x64           | `mcr.microsoft.com/dotnet-buildtools/prereqs:azurelinux-3.0-net10.0-webassembly-amd64`   | `/crossrootfs/x64`     |
-| Debian (x64)      | Debian 12                  | x64           | `mcr.microsoft.com/dotnet-buildtools/prereqs:debian-12-gcc14-amd64`                     |        *N/A*           |
+| Debian (x64)      | Debian 12                  | x64           | `mcr.microsoft.com/dotnet-buildtools/prereqs:debian-12-gcc15-amd64`                     |        *N/A*           |
 | Ubuntu (x64)      | Tizen 9.0                  | Arm32 (armel) | `mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-22.04-cross-armel-tizen`            | `/crossrootfs/armel`   |
 | Ubuntu (x64)      | Ubuntu 20.04               | Arm32 (v6)    | `mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-20.04-cross-armv6-raspbian-10`      | `/crossrootfs/armv6`   |
 

eng/pipelines/common/platform-matrix.yml

@@ -348,7 +348,7 @@ jobs:
       targetRid: linux-x64
       platform: linux_x64
       shouldContinueOnError: ${{ parameters.shouldContinueOnError }}
-      container: debian-12-gcc14-amd64
+      container: debian-12-gcc15-amd64
       jobParameters:
         runtimeFlavor: ${{ parameters.runtimeFlavor }}
         buildConfig: ${{ parameters.buildConfig }}

eng/pipelines/common/templates/pipeline-with-resources.yml

@@ -107,8 +107,8 @@ extends:
         env:
           ROOTFS_DIR: /crossrootfs/loongarch64
 
-      debian-12-gcc14-amd64:
-        image: mcr.microsoft.com/dotnet-buildtools/prereqs:debian-12-gcc14-amd64
+      debian-12-gcc15-amd64:
+        image: mcr.microsoft.com/dotnet-buildtools/prereqs:debian-12-gcc15-amd64
 
       linux_x64_llvmaot:
         image: mcr.microsoft.com/dotnet-buildtools/prereqs:centos-stream8