IJPL-253116: disable FilePageCache buffers flushing on idle/focus lost

+ `FilePageCache` direct buffers were flushed and released on IDE focus lost + idle => caused freezes => not a lot of profit from it => disable by default


(cherry picked from commit df4075cd24a3e7563d81477cb93cda82d998a928)

IJ-CR-219603

GitOrigin-RevId: 187b25fa4425388a25637cd55b61ebcbab3f00dd

platform/platform-impl/src/com/intellij/ide/AppIdleMemoryCleaner.kt

@@ -129,8 +129,10 @@ class AppIdleMemoryCleaner(private val cs: CoroutineScope) {
     stats.measureGc {
       runGc()
     }
-    stats.measureDirectBuffers {
-      releaseIndexCachedDirectBuffers()
+    if (!Registry.`is`("ide.idle.memory.cleaner.enabled.page.cache.release")) {
+      stats.measureDirectBuffers {
+        releaseIndexCachedDirectBuffers()
+      }
     }
 
     PlatformMemoryUtil.getInstance().trimLinuxNativeHeap()

platform/platform-resources/src/META-INF/PlatformExtensions.xml

@@ -2057,6 +2057,9 @@ The refresh itself is toggled by (Preferences | Appearance & Behavior | Syst
     <registryKey key="ide.idle.memory.cleaner.delay"
                  defaultValue="5000"
                  description="A delay in milliseconds between the IDE becoming idle and the memory cleaning being performed"/>
+    <registryKey key="ide.idle.memory.cleaner.enabled.page.cache.release"
+                 defaultValue="false"
+                 description="Flush and release allocated direct buffers to OS when IDE becomes idle"/>
     <registryKey key="progresses.show.counter.icon.instead.of.show.link"
                  defaultValue="true"
                  description="Progresses would be shown with an icon with their number in status bar instead of Show All link"/>