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/test/test-bpf-restrict-fsaccess.c

@@ -107,7 +107,7 @@ static int do_attach(void) {
         struct stat st;
         int r;
 
-        r = dlopen_bpf(LOG_ERR);
+        r = DLOPEN_BPF(LOG_ERR, SD_ELF_NOTE_DLOPEN_PRIORITY_RECOMMENDED);
         if (r < 0)
                 return log_error_errno(r, "Failed to dlopen libbpf: %m");
 

src/test/test-bpf-token.c

@@ -11,7 +11,7 @@ static int run(int argc, char *argv[]) {
 #if HAVE_LIBBPF
         int r;
 
-        r = dlopen_bpf(LOG_ERR);
+        r = DLOPEN_BPF(LOG_ERR, SD_ELF_NOTE_DLOPEN_PRIORITY_RECOMMENDED);
         if (r < 0)
                 return r;