PHPLIB-826: Remove use of admin database in CSFLE driver doc examples

Author: aleksandr-rudo

docs/tutorial/client-side-encryption.txt

@@ -35,7 +35,7 @@ encrypted on insertion and decrypted when querying on the client side.
    $localKey = new Binary('<binary key data (96 bytes)>', Binary::TYPE_GENERIC);
 
    $encryptionOpts = [
-       'keyVaultNamespace' => 'admin.datakeys',
+       'keyVaultNamespace' => 'encryption.__keyVault',
        'kmsProviders' => [
            'local' => ['key' => $localKey],
        ],
@@ -101,7 +101,7 @@ encryption using the newly created key.
    $localKey = new Binary('<binary key data (96 bytes)>', Binary::TYPE_GENERIC);
 
    $clientEncryptionOpts = [
-       'keyVaultNamespace' => 'admin.datakeys',
+       'keyVaultNamespace' => 'encryption.__keyVault',
        'kmsProviders' => [
            'local' => ['key' => $localKey],
        ],
@@ -114,7 +114,7 @@ encryption using the newly created key.
    $keyId = $clientEncryption->createDataKey('local');
 
    $autoEncryptionOpts = [
-       'keyVaultNamespace' => 'admin.datakeys',
+       'keyVaultNamespace' => 'encryption.__keyVault',
        'kmsProviders' => [
            'local' => ['key' => $localKey],
        ],
@@ -163,7 +163,7 @@ explicitly encrypts and decrypts values in the document.
    $localKey = new Binary('<binary key data (96 bytes)>', Binary::TYPE_GENERIC);
 
    $clientEncryptionOpts = [
-       'keyVaultNamespace' => 'admin.datakeys',
+       'keyVaultNamespace' => 'encryption.__keyVault',
        'kmsProviders' => [
            'local' => ['key' => $localKey],
        ],
@@ -212,7 +212,7 @@ The software then encrypts data by referencing the key by its alternative name.
    $localKey = new Binary('<binary key data (96 bytes)>', Binary::TYPE_GENERIC);
 
    $clientEncryptionOpts = [
-       'keyVaultNamespace' => 'admin.datakeys',
+       'keyVaultNamespace' => 'encryption.__keyVault',
        'kmsProviders' => [
            'local' => ['key' => $localKey],
        ],