bench: refactor to use string interpolation in buffer/from-string

PR-URL: #9579
Ref: #8647

Reviewed-by: Philipp Burckhardt <pburckhardt@outlook.com>

Author: whizzel

lib/node_modules/@stdlib/buffer/from-string/benchmark/benchmark.length.js

@@ -23,6 +23,7 @@
 var bench = require( '@stdlib/bench' );
 var pow = require( '@stdlib/math/base/special/pow' );
 var isBuffer = require( '@stdlib/assert/is-buffer' );
+var format = require( '@stdlib/string/format' );
 var pkg = require( './../package.json' ).name;
 var string2buffer = require( './../lib' );
 
@@ -93,7 +94,7 @@ function main() {
 	for ( i = min; i <= max; i++ ) {
 		len = pow( 10, i );
 		f = createBenchmark( len );
-		bench( pkg+':len='+len, f );
+		bench( format( '%s:len=%d', pkg, len ), f );
 	}
 }