This fixes a missed bug introduced in #4510.
Because the regexp was `/-[^-]*/` and not `/-[^-]*$/`, a wrong part of the filename was being removed:
```
bad:
'foo-bar-0123456789abcdef-0123456789abcdef.js' -> 'foo-0123456789abcdef-0123456789abcdef.js'
good:
'foo-bar-0123456789abcdef-0123456789abcdef.js' -> 'foo-bar-0123456789abcdef'
```
By a stroke of luck this didn't affect the existing dynamically generated chunks. To prevent regression I've added unit tests for the function that generates the name.
Btw. in the original issue (#4433) I used the right regexp, I just used the wrong regexp in #4510.
cc @timneutkens
