Allow dynamic configuration of maximum attribute collection size

[loewenheim]

Eventually we want to make the maximum total size of attributes configurable at runtime, probably via the project config. I can see two ways to accomplish this:

1. Pass the size into the EAP trimming processor as a parameter. This works but is pretty inelegant (why is the size of this one particular datum a property of the processor and not the value, like in all other cases)?
2. Extend the functionality for dynamic computation of max_bytes we're adding in feat: Add dynamic max_bytes/max_chars definition #5500: we could make the function that's used in the computation take a "context" parameter in addition to the processing state which would include the project config (a suitable type may already exist, else we'd have to define it).

Update: For spans, the attributes are the only data that should even be trimmed and be considered for size limits. For logs, there is additionally also the body. Therefore it may be much more straightforward to define a limit for the entire item.

[linear]

RELAY-191