bootc-ubuntu-setup: Check if packages exist before removal

The arm64 runners from Arm Limited don't have all the same packages
as x86_64 runners (e.g. google-chrome-stable). This caused apt-get
remove to fail with exit code 100.

Fix by checking with dpkg -l before attempting removal. Also switch
from regex patterns to globs since both apt and dpkg support fnmatch
globs, avoiding the need for pattern conversion.

Assisted-by: OpenCode (Claude claude-opus-4-5@20251101)
Signed-off-by: Colin Walters <walters@verbum.org>

Author: cgwalters

common/.github/actions/bootc-ubuntu-setup/action.yml

@@ -14,7 +14,8 @@ runs:
       run: |
         set -xeuo pipefail
         sudo df -h
-        unwanted_pkgs=('^aspnetcore-.*' '^dotnet-.*' '^llvm-.*' 'php.*' '^mongodb-.*' '^mysql-.*'
+        # Use globs for package patterns (apt and dpkg both support fnmatch globs)
+        unwanted_pkgs=('aspnetcore-*' 'dotnet-*' 'llvm-*' 'php*' 'mongodb-*' 'mysql-*'
                        azure-cli google-chrome-stable firefox mono-devel)
         unwanted_dirs=(/usr/share/dotnet /opt/ghc /usr/local/lib/android /opt/hostedtoolcache/CodeQL)
         # Start background removal operations as systemd units; if this causes
@@ -30,9 +31,12 @@ runs:
         for x in ${unwanted_dirs[@]}; do
           runcleanup rm -rf "$x"
         done
-        # Apt removals in foreground, as we can't parallelize these
+        # Apt removals in foreground, as we can't parallelize these.
+        # Only attempt removal if matching packages are installed.
         for x in ${unwanted_pkgs[@]}; do
-          /bin/time -f '%E %C' sudo apt-get remove -y $x
+          if dpkg -l "$x" >/dev/null 2>&1; then
+            /bin/time -f '%E %C' sudo apt-get remove -y "$x"
+          fi
         done
     # We really want support for heredocs
     - name: Update podman and install just