Remove usage of measurements in favor of span.data. (#92718)

Python SDK 3.0 removes measurements. This PR makes sure that we do not use `measurements` internally but rather
use `span.data` instead.

---------

Co-authored-by: Daniel Szoke <daniel.szoke@sentry.io>

Author: antonpirker

src/sentry/utils/sdk.py

@@ -3,6 +3,7 @@
 import copy
 import logging
 import sys
+import typing
 from collections.abc import Generator, Mapping, Sequence, Sized
 from types import FrameType
 from typing import TYPE_CHECKING, Any, NamedTuple
@@ -237,12 +238,15 @@ def before_send_transaction(event: Event, _: Hint) -> Event | None:
         num_of_spans = len(event["spans"])
 
     event["tags"]["spans_over_limit"] = str(num_of_spans >= 1000)
-    if not event["measurements"]:
-        event["measurements"] = {}
-    event["measurements"]["num_of_spans"] = {
-        "value": num_of_spans,
-        "unit": None,
-    }
+
+    # Type safety: `event["contexts"]["trace"]["data"]` is a dictionary if it is set.
+    # See https://develop.sentry.dev/sdk/data-model/event-payloads/contexts/#trace-context.
+    data = typing.cast(
+        dict[str, object],
+        event.setdefault("contexts", {}).setdefault("trace", {}).setdefault("data", {}),
+    )
+    data["num_of_spans"] = num_of_spans
+
     return event
 
 
@@ -695,15 +699,6 @@ def parse_org_slug(x: Organization | RpcOrganization | str) -> str:
     )
 
 
-def set_measurement(measurement_name, value, unit=None):
-    try:
-        transaction = sentry_sdk.Scope.get_current_scope().transaction
-        if transaction is not None:
-            transaction.set_measurement(measurement_name, value, unit)
-    except Exception:
-        pass
-
-
 def set_span_attribute(data_name, value):
     span = sentry_sdk.get_current_span()
     if span is not None:
@@ -746,6 +741,5 @@ def merge_context_into_scope(
     "patch_transport_for_instrumentation",
     "isolation_scope",
     "set_current_event_project",
-    "set_measurement",
     "traces_sampler",
 )