Remove deprecated `traceHeaders` method on `IHub` / `IScopes`

[adinauer]

Description

Should be removed in a major.

See

sentry-java/sentry/src/main/java/io/sentry/IHub.java

Lines 470 to 479 in 7b7964f

	/**
	* Returns the "sentry-trace" header that allows tracing across services. Can also be used in
	* <meta> HTML tags. Also see {@link IHub#getBaggage()}.
	*
	* @deprecated please use {@link IHub#getTraceparent()} instead.
	* @return sentry trace header or null
	*/
	@Deprecated
	@Nullable
	SentryTraceHeader traceHeaders();

Has been moved to IScopes for 8.x.x.