change the default builder and fix a typo

rpmbuild/build.sh

@@ -7,7 +7,7 @@ tmp_dir="$(mktemp -d -t mock-XXXXXXXXXX)"
 trap "rm -rf $tmp_dir" EXIT
 
 # List of available builders: ls -1 /etc/mock
-builder="${BUILDER:-centos-8-x86_64}"
+builder="${BUILDER:-centos-stream-8-x86_64}"
 echo "Using builder image $builder..."
 
 function build_pkgs () {
@@ -34,5 +34,5 @@ else
   build_pkgs SPECS/*.spec
 fi
 
-rm -f "$tmp_dir/*.src.rpm" "$tmp_dir/*.log"
+rm -f $tmp_dir/*.src.rpm $tmp_dir/*.log
 mv $tmp_dir/*.rpm RPMS/x86_64/