fix(core): check http_retry option instead of transport capability

cleanup_cache was gated on sentry__transport_can_retry, which checks
for retry_func. Since retry_func is unconditionally set for all HTTP
transports, this ran cleanup_cache even with http_retry disabled.
Check the option directly instead.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: jpnurmi

src/sentry_core.c

@@ -290,8 +290,7 @@ sentry_init(sentry_options_t *options)
         backend->prune_database_func(backend);
     }
 
-    if (options->cache_keep
-        || sentry__transport_can_retry(options->transport)) {
+    if (options->cache_keep || options->http_retry) {
         sentry__cleanup_cache(options);
     }