build: Remove usage of obsolescent egrep

* "egrep: warning: egrep is obsolescent; using grep -E"
* egrep on haiku is a shell script calling grep -E
* given the warnings in the latest egrep, lets get
  ahead of the curve and migrate to grep -E

Change-Id: I0fc2b936c7a9c52f87caf97d8e9ac42516fee014
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5718
Reviewed-by: Adrien Destugues <[email protected]>
Tested-by: Commit checker robot <[email protected]>

build/scripts/build_haiku_image

@@ -374,7 +374,7 @@ fi
 
 # install default settings for packages
 for packageFile in $systemPackages; do
-	if $package list -p $packageFile | egrep '^settings/' > /dev/null; then
+	if $package list -p $packageFile | grep -E '^settings/' > /dev/null; then
 		extractFile $packageFile system/settings settings
 	fi
 done