Revert "Recorder: Use medium localized datetime for filename"

This reverts commit ff23879.

Reason for revert: In some locale (e.g. Japanese) the change produces invalid filename that contains "/" (e.g. "Sound record (2024/09/29 19:15:33).wav"), breaking the app.

Change-Id: I7216cc3fb2897c993b526e5b9ed7ac2553aabb86

app/src/main/java/org/lineageos/recorder/RecorderActivity.kt

@@ -50,7 +50,7 @@ import org.lineageos.recorder.utils.Utils
 import org.lineageos.recorder.viewmodels.RecordingsViewModel
 import java.time.LocalDateTime
 import java.time.format.DateTimeFormatter
-import java.time.format.FormatStyle
+import java.time.format.DateTimeFormatterBuilder
 import java.time.temporal.ChronoUnit
 import java.util.Locale
 import kotlin.reflect.safeCast
@@ -373,9 +373,11 @@ class RecorderActivity : AppCompatActivity(R.layout.activity_main) {
     private val newRecordFileName: String
         get() {
             val tag = locationHelper.currentLocationName ?: FILE_NAME_FALLBACK
-            val formatter = DateTimeFormatter
-                .ofLocalizedDateTime(FormatStyle.MEDIUM)
-                .withLocale(Locale.getDefault())
+            val formatter = DateTimeFormatterBuilder()
+                .append(DateTimeFormatter.ISO_LOCAL_DATE)
+                .appendLiteral(' ')
+                .append(DateTimeFormatter.ISO_LOCAL_TIME)
+                .toFormatter(Locale.getDefault())
             val now = LocalDateTime.now()
             return String.format(
                 FILE_NAME_BASE, tag,