bench: refactor to use string interpolation in array/base/fliplr2d

PR-URL: #8857
Ref: #8647

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

Author: ullasrr

lib/node_modules/@stdlib/array/base/fliplr2d/benchmark/benchmark.size.js

@@ -27,6 +27,7 @@ var pow = require( '@stdlib/math/base/special/pow' );
 var floor = require( '@stdlib/math/base/special/floor' );
 var filled2dBy = require( '@stdlib/array/base/filled2d-by' );
 var numel = require( '@stdlib/ndarray/base/numel' );
+var format = require( '@stdlib/string/format' );
 var pkg = require( './../package.json' ).name;
 var fliplr2d = require( './../lib' );
 
@@ -100,7 +101,7 @@ function main() {
 		N = floor( pow( pow( 10, i ), 1.0/2.0 ) );
 		sh = [ N, N ];
 		f = createBenchmark( sh );
-		bench( pkg+'::square_matrix:size='+numel( sh ), f );
+		bench( format( '%s::square_matrix:size=%d', pkg, numel( sh ) ), f );
 	}
 }