minor #22895 Make internal constants private (chalasr)

This PR was merged into the 4.0-dev branch.

Discussion
----------

Make internal constants private

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

Changing some internal constants to private as suggested in #22862 (these are the only ones I found in the codebase)

Commits
-------

367b055 Make internal constants private

src/Symfony/Component/PropertyAccess/PropertyAccessor.php

@@ -32,90 +32,23 @@
  */
 class PropertyAccessor implements PropertyAccessorInterface
 {
-    /**
-     * @internal
-     */
-    const VALUE = 0;
-
-    /**
-     * @internal
-     */
-    const REF = 1;
-
-    /**
-     * @internal
-     */
-    const IS_REF_CHAINED = 2;
-
-    /**
-     * @internal
-     */
-    const ACCESS_HAS_PROPERTY = 0;
-
-    /**
-     * @internal
-     */
-    const ACCESS_TYPE = 1;
-
-    /**
-     * @internal
-     */
-    const ACCESS_NAME = 2;
-
-    /**
-     * @internal
-     */
-    const ACCESS_REF = 3;
-
-    /**
-     * @internal
-     */
-    const ACCESS_ADDER = 4;
-
-    /**
-     * @internal
-     */
-    const ACCESS_REMOVER = 5;
-
-    /**
-     * @internal
-     */
-    const ACCESS_TYPE_METHOD = 0;
-
-    /**
-     * @internal
-     */
-    const ACCESS_TYPE_PROPERTY = 1;
-
-    /**
-     * @internal
-     */
-    const ACCESS_TYPE_MAGIC = 2;
-
-    /**
-     * @internal
-     */
-    const ACCESS_TYPE_ADDER_AND_REMOVER = 3;
-
-    /**
-     * @internal
-     */
-    const ACCESS_TYPE_NOT_FOUND = 4;
-
-    /**
-     * @internal
-     */
-    const CACHE_PREFIX_READ = 'r';
-
-    /**
-     * @internal
-     */
-    const CACHE_PREFIX_WRITE = 'w';
-
-    /**
-     * @internal
-     */
-    const CACHE_PREFIX_PROPERTY_PATH = 'p';
+    private const VALUE = 0;
+    private const REF = 1;
+    private const IS_REF_CHAINED = 2;
+    private const ACCESS_HAS_PROPERTY = 0;
+    private const ACCESS_TYPE = 1;
+    private const ACCESS_NAME = 2;
+    private const ACCESS_REF = 3;
+    private const ACCESS_ADDER = 4;
+    private const ACCESS_REMOVER = 5;
+    private const ACCESS_TYPE_METHOD = 0;
+    private const ACCESS_TYPE_PROPERTY = 1;
+    private const ACCESS_TYPE_MAGIC = 2;
+    private const ACCESS_TYPE_ADDER_AND_REMOVER = 3;
+    private const ACCESS_TYPE_NOT_FOUND = 4;
+    private const CACHE_PREFIX_READ = 'r';
+    private const CACHE_PREFIX_WRITE = 'w';
+    private const CACHE_PREFIX_PROPERTY_PATH = 'p';
 
     /**
      * @var bool