bench: refactor to use string interpolation in blas/ext/base/dnancusumkbn

[rautelaKamal]

Ref #8647.

Description

What is the purpose of this pull request?

This pull request:

• Refactors the JavaScript benchmarks in @stdlib/blas/ext/base/dcusumpw to use string interpolation via @stdlib/string/format instead of string concatenation for constructing benchmark names.

Related Issues

This pull request resolves a part of #8647.

Checklist

• Read, understood, and followed the contributing guidelines
• Updated JavaScript benchmarks to use @stdlib/string/format.
• Verified benchmark names are preserved after refactoring.

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
blas/ext/base/dcusum	$\color{green}367/367$ $\color{green}+100.00%$	$\color{green}13/13$ $\color{green}+100.00%$	$\color{green}4/4$ $\color{green}+100.00%$	$\color{green}367/367$ $\color{green}+100.00%$
blas/ext/base/dcusumpw	$\color{green}418/418$ $\color{green}+100.00%$	$\color{green}18/18$ $\color{green}+100.00%$	$\color{green}4/4$ $\color{green}+100.00%$	$\color{green}418/418$ $\color{green}+100.00%$

The above coverage report was generated for the changes in this PR.