ci: stop set -e from aborting USB boot-entry detection

The PARTUUID match (Strategy 1) runs grep against efibootmgr output;
when the USB entry has no HD(GPT,<partuuid>) device path, grep exits
non-zero. Under set -euo pipefail that failing command substitution
aborted the whole remote script right after printing the boot entries,
before Strategy 2/3 or the error handler could run -- so the flash
succeeded but the stage failed with no diagnostic (seen in run #84).

Add `|| true` to the grep substitutions and lsblk calls so a legitimate
no-match falls through to the next strategy. Simulated against real #84
efibootmgr output (resolves to the USB entry), a generic no-brand stick
(USB-label match), and a no-USB host (reaches the error handler).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: mparamas-zz

Jenkinsfile

@@ -669,26 +669,29 @@ USB_ENTRY=""
 
 # Strategy 1: match a partition PARTUUID of the target device (works if the installer
 # wrote an ESP the firmware indexed as HD(GPT,<partuuid>)).
-for uuid in $(lsblk -no PARTUUID "$USB_DEVICE" 2>/dev/null); do
+# NOTE: each match uses `|| true` because a no-match grep exits non-zero, which under
+# `set -euo pipefail` would abort the whole script mid-detection before later strategies
+# (or the error handler below) get a chance to run.
+for uuid in $(lsblk -no PARTUUID "$USB_DEVICE" 2>/dev/null || true); do
     [ -z "$uuid" ] && continue
-    m=$(echo "$EFI_OUT" | grep -iE "^Boot[0-9A-Fa-f]{4}.*${uuid}" | grep -oE '^Boot[0-9A-Fa-f]{4}' | head -1 | sed 's/^Boot//')
+    m=$(echo "$EFI_OUT" | grep -iE "^Boot[0-9A-Fa-f]{4}.*${uuid}" | grep -oE '^Boot[0-9A-Fa-f]{4}' | head -1 | sed 's/^Boot//' || true)
     if [ -n "$m" ]; then USB_ENTRY="$m"; echo "Matched USB boot entry by PARTUUID ${uuid}."; break; fi
 done
 
 # Strategy 2: match by the target device's model/vendor tokens (ties the entry to THIS
 # exact USB drive, avoiding a wrong pick if several USB entries exist).
 if [ -z "$USB_ENTRY" ]; then
-    MODELVEND="$(lsblk -dno MODEL "$USB_DEVICE" 2>/dev/null) $(lsblk -dno VENDOR "$USB_DEVICE" 2>/dev/null)"
+    MODELVEND="$(lsblk -dno MODEL "$USB_DEVICE" 2>/dev/null || true) $(lsblk -dno VENDOR "$USB_DEVICE" 2>/dev/null || true)"
     for tok in $(echo "$MODELVEND" | tr '_/.-' '    '); do
         [ ${#tok} -ge 4 ] || continue
-        m=$(echo "$EFI_OUT" | grep -E '^Boot[0-9A-Fa-f]{4}' | grep -iF "$tok" | grep -oE '^Boot[0-9A-Fa-f]{4}' | head -1 | sed 's/^Boot//')
+        m=$(echo "$EFI_OUT" | grep -E '^Boot[0-9A-Fa-f]{4}' | grep -iF "$tok" | grep -oE '^Boot[0-9A-Fa-f]{4}' | head -1 | sed 's/^Boot//' || true)
         if [ -n "$m" ]; then USB_ENTRY="$m"; echo "Matched USB boot entry by device token '${tok}'."; break; fi
     done
 fi
 
 # Strategy 3: match the firmware's removable USB entry by "USB" in its description.
 if [ -z "$USB_ENTRY" ]; then
-    m=$(echo "$EFI_OUT" | grep -E '^Boot[0-9A-Fa-f]{4}' | grep -iE 'usb' | grep -oE '^Boot[0-9A-Fa-f]{4}' | head -1 | sed 's/^Boot//')
+    m=$(echo "$EFI_OUT" | grep -E '^Boot[0-9A-Fa-f]{4}' | grep -iE 'usb' | grep -oE '^Boot[0-9A-Fa-f]{4}' | head -1 | sed 's/^Boot//' || true)
     if [ -n "$m" ]; then USB_ENTRY="$m"; echo "Matched USB boot entry by 'USB' description."; fi
 fi