fix(lsphp-apt-upgrade): no early-exit readers under pipefail

apt-cache madison | grep -q and apt-cache policy | awk '...exit' can SIGPIPE
the writer under pipefail and report lsphp missing when it is there. Read
each output into a variable and match in the shell. Fixes the Shell-Checks
failure on trunk (lsphp-info-probe.test.sh structural scan).

Tested: lsphp-info-probe.test.sh 36/36, shellcheck clean, and the script run
in litespeedtech/openlitespeed:1.8.4-lsphp85 upgrades 8.5.0 -> 8.5.11 OK.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

scripts/lsphp-apt-upgrade.sh

@@ -49,11 +49,16 @@ echo "lsphp-apt-upgrade: base image lsphp${PHPVER}=$(dpkg-query -W -f='${Version
 
 # The candidate for lsphpNN must come from the LiteSpeed repo — not "none", and
 # not merely whatever is already installed.
-if ! apt-cache madison "lsphp${PHPVER}" | grep -q 'rpms.litespeedtech.com'; then
+# Read each output into a variable and match in the shell: piping into an
+# early-exit reader (grep -q, awk ... exit) under pipefail can SIGPIPE the writer
+# and report "missing" for a package that is there (scripts/tests/lsphp-info-probe.test.sh).
+MADISON=$(apt-cache madison "lsphp${PHPVER}")
+if [[ "$MADISON" != *rpms.litespeedtech.com* ]]; then
     apt-cache policy "lsphp${PHPVER}" >&2 || true
     die "the LiteSpeed apt repo does not offer lsphp${PHPVER} (repo missing from sources, or its index is empty)."
 fi
-CAND=$(apt-cache policy "lsphp${PHPVER}" | awk '/Candidate:/ {print $2; exit}')
+POLICY=$(apt-cache policy "lsphp${PHPVER}")
+CAND=$(awk '/Candidate:/ {print $2; exit}' <<<"$POLICY")
 echo "lsphp-apt-upgrade: repo candidate lsphp${PHPVER}=${CAND}"
 
 if [ "$OS_UPGRADE" = 1 ]; then