feat(misconf): Improve check registration and loading

[simar7]

Today checks are registered at startup of Trivy as done here. This has a few issues:

This has the overhead of adding unnecessary loading of checks into memory (and compute time) even if there is not misconfiguration scanning at play. This also can cause slowdowns as such: #7426
and #7431

We should register the checks explicitly when misconfiguration scanner is enabled rather than doing an init func to do so.