fix(utils): remove partial from mergeConfigs return type

[matejchalk]

Since the first parameter of mergeConfigs is a full CoreConfig, only the subsequent parameters are Partial<CoreConfig>s, then the result must be a full CoreConfig.

This removes the need to do mergeConfigs(...) as CoreConfig when using it.

[vmasek]

makes perfect sense, I do not recall why I left result partial (probably because all params were partial in initial design)

[github-actions]

Code PushUp

🤨 Code PushUp report has both improvements and regressions – compared current commit 038946a with previous commit ebb4ed5.

🕵️ See full comparison in Code PushUp portal 🔍

🏷️ Categories

🏷️ Category	⭐ Previous score	⭐ Current score	🔄 Score change
Performance	🟡 52	🟡 53
Code coverage	🟢 91	🟢 91	–
Security	🟡 75	🟡 75	–
Updates	🟡 77	🟡 77	–
Accessibility	🟢 92	🟢 92	–
Best Practices	🟢 100	🟢 100	–
SEO	🟡 61	🟡 61	–
Bug prevention	🟢 100	🟢 100	–
Code style	🟢 100	🟢 100	–
Documentation	🔴 23	🔴 23	–

👍 1 group improved, 👍 2 audits improved, 👎 3 audits regressed, 11 audits changed without impacting score

🗃️ Groups

🔌 Plugin	🗃️ Group	⭐ Previous score	⭐ Current score	🔄 Score change
Lighthouse	Performance	🟡 52	🟡 53

17 other groups are unchanged.

🛡️ Audits

🔌 Plugin	🛡️ Audit	📏 Previous value	📏 Current value	🔄 Value change
Lighthouse	Largest Contentful Paint	🟨 3.7 s	🟨 3.4 s
Lighthouse	Speed Index	🟨 5.2 s	🟨 5.5 s
Lighthouse	First Contentful Paint	🟨 2.8 s	🟨 2.7 s
Lighthouse	Total Blocking Time	🟥 2,900 ms	🟥 4,210 ms
Lighthouse	Time to Interactive	🟥 13.3 s	🟥 13.9 s
Lighthouse	Avoids enormous network payloads	🟩 Total size was 1,827 KiB	🟩 Total size was 1,832 KiB
Lighthouse	Minimizes main-thread work	🟥 12.4 s	🟥 15.6 s
Lighthouse	Metrics	🟩 100%	🟩 100%
Lighthouse	JavaScript execution time	🟥 6.5 s	🟥 7.0 s
Lighthouse	Eliminate render-blocking resources	🟥 Potential savings of 960 ms	🟥 Potential savings of 720 ms
Lighthouse	Max Potential First Input Delay	🟥 1,670 ms	🟥 1,890 ms
Lighthouse	Reduce unused CSS	🟥 Potential savings of 67 KiB	🟥 Potential savings of 56 KiB
Lighthouse	Server Backend Latencies	🟩 110 ms	🟩 70 ms
Lighthouse	Uses efficient cache policy on static assets	🟨 27 resources found	🟨 27 resources found
Lighthouse	Network Round Trip Times	🟩 20 ms	🟩 20 ms
Lighthouse	Initial server response time was short	🟩 Root document took 550 ms	🟩 Root document took 550 ms

580 other audits are unchanged.