ErrorProne: BluetoothMapContent

Remove a lot of unused code and empty javadoc tag
and the following

```
255: warning: Inner class is non-static but does not reference enclosing class
    private class FilterInfo {
            ^
449: warning: Caught exceptions should not be ignored
        } catch (IOException e) {
          ^
3567: warning: Non-exhaustive switch; either add a default or handle the remaining cases: NONE
        switch (type) {
        ^
```

Bug: 236759221
Test: m RUN_ERROR_PRONE=true Bluetooth
Change-Id: Ifcfdd59001556254771bbc11bcb0aae1807f9248