post-pbs-install: fix component_exists_in_sources matching substrings of hyphenated tokens

tools/pve/post-pbs-install.sh

@@ -62,7 +62,14 @@ repo_state_list() {
 
 component_exists_in_sources() {
   local component="$1"
-  grep -h -E "^[^#]*Components:[^#]*\b${component}\b" /etc/apt/sources.list.d/*.sources 2>/dev/null | grep -q .
+  local line comp
+  while IFS= read -r line; do
+    line="${line#*Components:}"
+    for comp in $line; do
+      [[ "$comp" == "$component" ]] && return 0
+    done
+  done < <(grep -h -E "^[^#]*Components:" /etc/apt/sources.list.d/*.sources 2>/dev/null)
+  return 1
 }
 
 require_whiptail() {