[gh-11363] Fix variable substitution in concat_lines for Linux compatibility

The previous implementation used AWK variables for substitution which didn't
work correctly on Linux systems. This commit separates the concerns:

1. Use sed for variable substitution ( and
   $MAVEN_PROJECTBASEDIR) - this is more portable and reliable across
   different Unix-like systems
2. Use awk only for escaping unquoted pipe symbols

This ensures that JVM config files work correctly on both macOS and Linux,
with proper variable substitution and pipe symbol handling.

Author: gnodet

apache-maven/src/assembly/maven/bin/mvn

@@ -167,16 +167,15 @@ find_file_argument_basedir() {
 
 # concatenates all lines of a file and replaces variables
 concat_lines() {
-  [ -f "$1" ] || return
-  
-  tr '\r' '\n' < "$1" | sed -e '/^$/d' -e 's/#.*$//' | awk \
-    -v maven_dir="${MAVEN_PROJECTBASEDIR//\\/\\\\}" '
+  if [ -f "$1" ]; then
+    # First pass: clean the file (convert CR to LF, remove empty lines and comments)
+    # and perform variable substitution using sed
+    tr '\r' '\n' < "$1" | sed -e '/^$/d' -e 's/#.*$//' | sed \
+      -e "s@\${MAVEN_PROJECTBASEDIR}@$MAVEN_PROJECTBASEDIR@g" \
+      -e "s@\$MAVEN_PROJECTBASEDIR@$MAVEN_PROJECTBASEDIR@g" | \
+    # Second pass: escape unquoted pipe symbols using awk
+    awk '
     {
-      # Replace variables
-      gsub(/\$\{MAVEN_PROJECTBASEDIR\}/, maven_dir)
-      gsub(/\$MAVEN_PROJECTBASEDIR/, maven_dir)
-      
-      # Escape unquoted pipe symbols
       result = ""
       in_quotes = 0
       for (i = 1; i <= length($0); i++) {
@@ -188,13 +187,14 @@ concat_lines() {
         }
         result = result char
       }
-      
+
       # Accumulate lines with space separator
       if (NR > 1) printf " "
       printf "%s", result
     }
     END { print "" }
-  '
+    '
+  fi
 }
 
 MAVEN_PROJECTBASEDIR="`find_maven_basedir "$@"`"