refactor: split collect_chunks into two methods (#1021)

# What does this PR do?

This refactor splits the logic in `collect_trace_chunks` between the trace exporter spans (v04 and v05) and the mini agent spans (pb::Spans).
it completely removes usage of the `TraceCollection` struct from data-pipeline, and instead introduces the `TraceChunks` enum to differentiate between v04 and v05.
 
Currently the way the code is structured makes replacing ByteString with the slice harder due to shared lifetime.
Furthermore, the enums encodes two different codepaths, the spanBytes and span pb which never interact with each other. So having function that handle both span bytes and pb spans is pure complexity overhead.
This refactor also removes a bunch of panics and lines of code that were here because to handle the "fake" pb spans and trace exporter spans overlap, which is practice never happens.

Lastly, this remove the TracerParams struct. Every occurence of if was creating it, and invoking `TryInto<TracerCollection>` just after on it. So replacing it by a simple function is a lot less complex for the same feature set.

# Motivation

Prepare for using `SpanSlice<'a>` instead of `SpanBytes` in the trace exporter.

Author: paullegranddc

src/trace_processor.rs

@@ -13,7 +13,7 @@ use datadog_trace_obfuscation::obfuscate::obfuscate_span;
 use datadog_trace_protobuf::pb;
 use datadog_trace_utils::trace_utils::{self};
 use datadog_trace_utils::trace_utils::{EnvironmentType, SendData};
-use datadog_trace_utils::tracer_payload::{TraceChunkProcessor, TraceCollection};
+use datadog_trace_utils::tracer_payload::TraceChunkProcessor;
 
 use crate::{
     config::Config,
@@ -96,15 +96,14 @@ impl TraceProcessor for ServerlessTraceProcessor {
             }
         };
 
-        let payload = match trace_utils::collect_trace_chunks(
-            TraceCollection::V07(traces),
+        let payload = match trace_utils::collect_pb_trace_chunks(
+            traces,
             &tracer_header_tags,
             &mut ChunkProcessor {
                 config: config.clone(),
                 mini_agent_metadata: mini_agent_metadata.clone(),
             },
             true, // In mini agent, we always send agentless
-            false,
         ) {
             Ok(res) => res,
             Err(err) => {