fix: information disclosure bug in preconditions GET (#19810)

precondition check was being honored before, validating
if anonymous access is allowed on the metadata of an
object, leading to metadata disclosure of the following
headers.

```
Last-Modified
Etag
x-amz-version-id
Expires:
Cache-Control:
```

although the information presented is minimal in nature,
and of opaque nature. It still simply discloses that an
object by a specific name exists or not without even having
enough permissions.

.gitignore

@@ -43,4 +43,13 @@ docs/debugging/inspect/inspect
 docs/debugging/pprofgoparser/pprofgoparser
 docs/debugging/reorder-disks/reorder-disks
 docs/debugging/populate-hard-links/populate-hardlinks
-docs/debugging/xattr/xattr
+docs/debugging/xattr/xattr
+hash-set
+healing-bin
+inspect
+pprofgoparser
+reorder-disks
+s3-check-md5
+s3-verify
+xattr
+xl-meta