tree-wide: convert dlopen_*() callers to DLOPEN_* wrapper macros

Switch the executable-owned call sites from the plain dlopen_<lib>()
helpers to the new DLOPEN_<LIB>() macros, so that each binary that loads
an optional library at runtime now carries its own .note.dlopen note
instead of relying solely on libsystemd-shared. Each call site passes a
priority reflecting whether it hard-depends on the library (required) or
degrades gracefully without it (recommended).

Co-developed-by: Claude Opus 4.8 <noreply@anthropic.com>

src/report/report-upload.c

@@ -81,7 +81,7 @@ static int http_upload_collected(Context *context, sd_json_variant *report) {
         _cleanup_free_ char *json = NULL;
         int r;
 
-        r = dlopen_curl(LOG_DEBUG);
+        r = DLOPEN_CURL(LOG_DEBUG, SD_ELF_NOTE_DLOPEN_PRIORITY_REQUIRED);
         if (r < 0)
                 return r;