use sed substitute instead of delete and append (#4555)

* use sed substitute instead of delete and append

doesn't move the line to the end of the file, instead keeps the order of the lines in setupVars.conf intact

Signed-off-by: Lukas Schlötterer <80917404+lschloetterer@users.noreply.github.com>

* Match start of line

as suggested in the review

Signed-off-by: Lukas Schlötterer <80917404+lschloetterer@users.noreply.github.com>

Co-authored-by: yubiuser <ckoenig@posteo.de>

Co-authored-by: yubiuser <ckoenig@posteo.de>

pihole

@@ -223,8 +223,7 @@ Time:
       fi
 
       local str="Pi-hole Disabled"
-      sed -i "/BLOCKING_ENABLED=/d" "${setupVars}"
-      echo "BLOCKING_ENABLED=false" >> "${setupVars}"
+      sed -i "s/^BLOCKING_ENABLED=true/BLOCKING_ENABLED=false/" "${setupVars}"
     fi
   else
     # Enable Pi-hole
@@ -236,8 +235,7 @@ Time:
     echo -e "  ${INFO} Enabling blocking"
     local str="Pi-hole Enabled"
 
-    sed -i "/BLOCKING_ENABLED=/d" "${setupVars}"
-    echo "BLOCKING_ENABLED=true" >> "${setupVars}"
+    sed -i "s/^BLOCKING_ENABLED=false/BLOCKING_ENABLED=true/" "${setupVars}"
   fi
 
   restartDNS reload-lists