[FrameworkBundle] Fixes invalid serialized objects in cache

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #6203

Fixes 2 problems:
*  malformed router chache filenames (matcher & dumper)
*  invalid cache file paths in serialized objects (.meta files)