`EntityCache` leaks memory & prone to inconsistencies & race conditions

### Describe the bug

`org.apache.polaris.core.persistence.cache.EntityCache` uses two containers:

```java
private final Cache byId;
private final AbstractMap byName;
```

The first one is a Caffeine cache, the second one is a Java Map.

`byName` can become inconsistent due to race conditions, multiple threads acting on the same entity IDs and/or entity names.
The implementation assumes, that there are no multi-threaded accesses against the same entity IDs and/or entity names, which is not guaranteed.

### To Reproduce

_No response_

### Actual Behavior

_No response_

### Expected Behavior

_No response_

### Additional context

_No response_

### System information

_No response_

Start by reading org.apache.polaris.core.persistence.cache.EntityCache, focusing on the Caffeine byId cache and the Java byName map. Investigate concurrent accesses involving the same entity IDs or names; done means the cache no longer leaks memory or allows byName to become inconsistent.

Written by the indexing model from the issue text.