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

PR-URL: #10647
Ref: #8647
Reviewed-by: Athan Reines <kgryte@gmail.com>

Author: JavaTypedScript

lib/node_modules/@stdlib/array/base/first/benchmark/benchmark.js

@@ -25,6 +25,7 @@ var discreteUniform = require( '@stdlib/random/base/discrete-uniform' ).factory;
 var pow = require( '@stdlib/math/base/special/pow' );
 var filledBy = require( '@stdlib/array/filled-by' );
 var isnanf = require( '@stdlib/math/base/assert/is-nanf' );
+var format = require( '@stdlib/string/format' );
 var pkg = require( './../package.json' ).name;
 var first = require( './../lib' );
 
@@ -95,7 +96,7 @@ function main() {
 		len = pow( 10, i );
 
 		f = createBenchmark( len );
-		bench( pkg+':len='+len, f );
+		bench( format( '%s:len=%d', pkg, len ), f );
 	}
 }