Refactor Weave integration

[anakin87]

As reported in #2038, when working on fixing types, I discovered that currently
the Weave Tracer violates of the Liskov Substitution Principle and fixing this does not seem straightforward.

haystack-core-integrations/integrations/weights_and_biases_weave/src/haystack_integrations/tracing/weave/tracer.py

Lines 157 to 159 in 14fd1b8

	# the current implementation violates the Liskov Substitution Principle by using WeaveSpan instead of Span
	# unfortunately, it seems hard to fix without rewriting the Tracer
	parent_span: Optional[WeaveSpan] = None, # type: ignore[override]

Since I'm not an expert on this integration, I can't confidently say if this is problematic or no.
(Langfuse might have similar problems but I am not sure).

We should evaluate whether this causes practical problems and if it's worth refactoring the integration to address it.

[sjrl]

(Langfuse might have similar problems but I am not sure)

Just to comment on the Langfuse integration, it looks to not have this problem. When looking here

haystack-core-integrations/integrations/langfuse/src/haystack_integrations/tracing/langfuse/tracer.py

Lines 425 to 428 in 14fd1b8

	@contextlib.contextmanager
	def trace(
	self, operation_name: str, tags: Optional[Dict[str, Any]] = None, parent_span: Optional[Span] = None
	) -> Iterator[Span]:

I checked that it's trace function returns the Span from Haystack.