Revert "chase: invert CHASE_NO_AUTOFS and only set it where needed"

This reverts commit 490aa05ca1.

As commented https://github.com/systemd/systemd/pull/38569#discussion_r2284978273,
the commit makes autofs check bypassed. Before the commit, when
CHASE_NO_AUTOFS is set, we did not shortcut chasing paths, and refused
any autofs mount points in the path. However, with the commit, the flag
was swapped but even when CHASE_AUTOFS is unset, the autofs check may be
skipped.

To fix the issue, rather than swapping the flag, we should introduce
another flag, say CHASE_TRIGGER_AUTOFS. This revert the commit, and in a
later commit, the new flag will be introduced.

src/basic/chase.h

@@ -6,7 +6,7 @@
 typedef enum ChaseFlags {
         CHASE_PREFIX_ROOT        = 1 << 0,  /* The specified path will be prefixed by the specified root before beginning the iteration */
         CHASE_NONEXISTENT        = 1 << 1,  /* It's OK if the path doesn't actually exist. */
-        CHASE_AUTOFS             = 1 << 2,  /* Trigger automount if autofs mount point found instead of returning -EREMOTE */
+        CHASE_NO_AUTOFS          = 1 << 2,  /* Return -EREMOTE if autofs mount point found */
         CHASE_SAFE               = 1 << 3,  /* Return -EPERM if we ever traverse from unprivileged to privileged files or directories */
         CHASE_TRAIL_SLASH        = 1 << 4,  /* Any trailing slash will be preserved */
         CHASE_STEP               = 1 << 5,  /* Just execute a single step of the normalization */