chore(publish): add test for _auth with configured registry

[wraithgar]

During #4763 it became apparent there was a test missing to show how _auth works with a configured registry (not a scope-configured registry)

[npm-robot]

no statistically significant performance changes detected

timing results

app-large	clean	lock-only	cache-only	cache-only peer-deps	modules-only	no-lock	no-cache	no-modules	no-clean	no-clean audit
npm@8	55.949 ±4.22	34.873 ±0.28	27.778 ±9.72	23.088 ±0.48	3.456 ±0.02	3.510 ±0.02	2.821 ±0.01	13.185 ±0.04	2.797 ±0.05	3.938 ±0.03
#4791	57.493 ±3.33	35.252 ±0.15	20.356 ±0.12	23.157 ±0.36	3.478 ±0.03	3.470 ±0.03	2.813 ±0.02	13.397 ±0.06	2.823 ±0.01	4.037 ±0.00

app-medium	clean	lock-only	cache-only	cache-only peer-deps	modules-only	no-lock	no-cache	no-modules	no-clean	no-clean audit
npm@8	41.578 ±0.36	26.921 ±0.34	15.185 ±0.10	16.283 ±0.20	3.170 ±0.06	3.205 ±0.04	2.841 ±0.04	9.905 ±0.10	2.665 ±0.01	3.624 ±0.04
#4791	42.184 ±0.69	27.297 ±0.08	15.003 ±0.14	16.258 ±0.72	3.158 ±0.05	3.154 ±0.05	2.834 ±0.06	10.002 ±0.10	2.667 ±0.00	3.601 ±0.08