bench: refactor to use string interpolation in array/base/filled4d

PR-URL: #9186
Ref: #8647

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

Author: JavaTypedScript

lib/node_modules/@stdlib/array/base/filled4d/benchmark/benchmark.size.js

@@ -24,6 +24,7 @@ var bench = require( '@stdlib/bench' );
 var pow = require( '@stdlib/math/base/special/pow' );
 var floor = require( '@stdlib/math/base/special/floor' );
 var isArrayArray = require( '@stdlib/assert/is-array-array' );
+var format = require( '@stdlib/string/format' );
 var pkg = require( './../package.json' ).name;
 var filled4d = require( './../lib' );
 
@@ -88,7 +89,7 @@ function main() {
 		N = floor( pow( pow( 10, i ), 1.0/4.0 ) );
 
 		f = createBenchmark( N );
-		bench( pkg+'::equidimensional:size='+(N*N*N*N), f );
+		bench( format( '%s::equidimensional:size=%d', pkg, N*N*N*N ), f );
 	}
 }