Rework span start and end lifecycle hook emission

[Lms24]

Currently, the behaviour for spanStart and spanEnd/afterSpanEnd client hook event emissions is a bit inconsistent across SDKs and span types

Sentry Spans (non-OTel path)

Case	Span class	spanStart	spanEnd	Notes
Sampled root	SentrySpan	Yes	Yes (via _onSpanEnded)
Negatively sampled root	SentrySpan (sampled: false)	Yes	Yes (via _onSpanEnded)	Hooks fire, listeners must guard themselves
Sampled child	SentrySpan	Yes	Yes (via _onSpanEnded)
Negatively sampled child	SentryNonRecordingSpan	Yes	No (end() is no-op)	Unpaired! spanStart fires, spanEnd never does
Ignored span	SentryNonRecordingSpan	No (returns before _startChildSpan)	No
onlyIfParent, no parent	SentryNonRecordingSpan	No (created before createChildOrRootSpan)	No
Tracing disabled	SentryNonRecordingSpan	No (hasSpansEnabled() = false)	No

OTel Spans

Case	OTel SamplingDecision	Reaches processor?	spanStart	spanEnd
Sampled root	RECORD_AND_SAMPLED	Yes	Yes	Yes
Negatively sampled root	NOT_RECORD	No	No	No
Sampled child	RECORD_AND_SAMPLED	Yes	Yes	Yes
Negatively sampled child	NOT_RECORD	No	No	No
Ignored span	NOT_RECORD	No	No	No

Goals

• We need to align on the behaviour and at the very least fix the unpaired occurance of the negatively sampled child span scenario
• We simplify which actor emits the events. Ideally, only the span classes (Sentry) and span processor (OTel) emit the hooks. Though this can be challenging with the cases where we early return for ignored/no_parent_span cases.

[linear-code]

JS-2693