[lldb][NFC] Always update m_cache_{hits/misses} in FormatCache

Summary:
These two variables are only incremented under LLDB_CONFIGURATION_DEBUG but their
value is always logged when verbose lldb formatter logging is enabled, which causes that our
cache hit/miss log looks like this in non-Debug builds:

```
Cache hits: 0 - Cache Misses: 0
...
Cache hits: 0 - Cache Misses: 0
...
Cache hits: 0 - Cache Misses: 0
```

This just always increments those two counters independent of build mode.

Reviewers: JDevlieghere

Reviewed By: JDevlieghere

Differential Revision: https://reviews.llvm.org/D76687