systemctl: gracefully adjust bus transport and runtime scope when --boot-loader-entry=help

This fixes the following assertion:
===
SYSTEMD_LOG_LEVEL=debug systemctl --user -H foo --boot-loader-entry=help
Assertion 'transport != BUS_TRANSPORT_REMOTE || runtime_scope == RUNTIME_SCOPE_SYSTEM' failed at src/shared/bus-util.c:284, function bus_connect_transport(). Ignoring.
Failed to connect to bus: Operation not supported
===

Fixes a bug introduced by 97af80c5a7.
Fixes #33661.
Fixes oss-fuzz#70153.

src/systemctl/systemctl-logind.c

@@ -432,6 +432,14 @@ int help_boot_loader_entry(void) {
         sd_bus *bus;
         int r;
 
+        /* This is called without checking runtime scope and bus transport like we do in parse_argv().
+         * Loading boot entries is only supported by system scope. Let's gracefully adjust them. */
+        arg_runtime_scope = RUNTIME_SCOPE_SYSTEM;
+        if (arg_transport == BUS_TRANSPORT_CAPSULE) {
+                arg_host = NULL;
+                arg_transport = BUS_TRANSPORT_LOCAL;
+        }
+
         r = acquire_bus(BUS_FULL, &bus);
         if (r < 0)
                 return r;