[4.x] Change nocache performance optimizations to be opt-in (#9124)

src/StaticCaching/NoCache/Tags.php

@@ -23,8 +23,11 @@ public function index()
     {
         if ($this->params->has('select')) {
             $fields = $this->params->explode('select');
-        } elseif (config('statamic.antlers.version') === 'runtime') {
-            $fields = Antlers::identifiers($this->content);
+
+            if (in_array('@auto', $fields)) {
+                $identifiers = Antlers::identifiers($this->content);
+                $fields = array_merge(array_diff($fields, ['@auto']), $identifiers);
+            }
         }
 
         return $this

tests/StaticCaching/NocacheTagsTest.php

@@ -106,10 +106,13 @@ public function it_can_keep_nested_nocache_tags_dynamic_inside_cache_tags()
     /** @test */
     public function it_only_adds_appropriate_fields_of_context_to_session()
     {
-        // We will not add `baz` to the session because it is not used in the template.
-        // We will not add `nope` to the session because it is not in the context.
-        $expectedFields = ['foo', 'bar'];
-        $template = '{{ nocache }}{{ foo }}{{ bar }}{{ nope }}{{ /nocache }}';
+        $expectedFields = [
+            'foo', // By adding @auto it will be picked up from the template.
+            'baz', // Explicitly selected
+            // 'bar' // Not explicitly selected
+            // 'nope' // Not in the context
+        ];
+        $template = '{{ nocache select="@auto|baz" }}{{ foo }}{{ nope }}{{ /nocache }}';
         $context = [
             'foo' => 'alfa',
             'bar' => 'bravo',