Fixes #3641 Use finish() instead of intent for smoother navigation (#5557)

## Description:
- Fixes #3641  
This PR simplifies the navigation logic in `AddProfileActivity` and
documents the reasoning behind not using `finish()` in
`ExitProfileDialogFragment`.

### Changes Made:
- **AddProfileActivity:**  
- Replaced the use of `Intent` with `FLAG_ACTIVITY_CLEAR_TOP` by calling
`finish()`.
- With the live data bug resolved, the activity stack can now be managed
more cleanly without requiring a new intent.

  **Benefits:**  
  - Avoids unnecessary activity recreation.  
  - Improves navigation efficiency and reduces overhead.  

- **ExitProfileDialogFragment:**  
- Retained the use of an `Intent` to navigate to
`ProfileChooserActivity` instead of switching to `finish()`.
  - **Reason:**  
- `ProfileChooserActivity` is not directly below the current activity in
the stack.
- If `finish()` were used, the app would incorrectly navigate to
`PinPasswordActivity`, resulting in undesirable behavior.

### Testing:
1. Verified that `AddProfileActivity` correctly navigates back to
`ProfileChooserActivity` using `finish()` without activity recreation.
2. Confirmed that `ExitProfileDialogFragment` behaves as expected,
retaining the correct navigation path through `Intent` to
`ProfileChooserActivity`.

### Summary:
This PR ensures cleaner navigation for `AddProfileActivity` by using
`finish()`, while maintaining correct behavior in
`ExitProfileDialogFragment` by continuing to use an intent-based
approach. This makes the app more efficient while preserving user
experience.

### Video Demo as everything is working fine.

https://github.com/user-attachments/assets/fb383845-5672-4236-8618-a87583cbbba0



## Essential Checklist
- [x] The PR title and explanation each start with "Fix #bugnum: " (If
this PR fixes part of an issue, prefix the title with "Fix part of
#bugnum: ...".)
- [x] Any changes to
[scripts/assets](https://github.com/oppia/oppia-android/tree/develop/scripts/assets)
files have their rationale included in the PR explanation.
- [x] The PR follows the [style
guide](https://github.com/oppia/oppia-android/wiki/Coding-style-guide).
- [x] The PR does not contain any unnecessary code changes from Android
Studio
([reference](https://github.com/oppia/oppia-android/wiki/Guidance-on-submitting-a-PR#undo-unnecessary-changes)).
- [x] The PR is made from a branch that's **not** called "develop" and
is up-to-date with "develop".
- [x] The PR is **assigned** to the appropriate reviewers
([reference](https://github.com/oppia/oppia-android/wiki/Guidance-on-submitting-a-PR#clarification-regarding-assignees-and-reviewers-section)).

Author: theayushyadav11

app/src/main/java/org/oppia/android/app/drawer/ExitProfileDialogFragment.kt

@@ -70,7 +70,6 @@ class ExitProfileDialogFragment : InjectableDialogFragment() {
         dialog.dismiss()
       }
       .setPositiveButton(R.string.home_activity_back_dialog_exit) { _, _ ->
-        // TODO(#3641): Investigate on using finish instead of intent.
         val intent = ProfileChooserActivity.createProfileChooserActivity(activity!!)
         if (!restoreLastCheckedItem) {
           intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP)

app/src/main/java/org/oppia/android/app/profile/AddProfileActivity.kt

@@ -44,10 +44,7 @@ class AddProfileActivity : InjectableAutoLocalizedAppCompatActivity() {
   }
 
   override fun onSupportNavigateUp(): Boolean {
-    // TODO(#3641): Investigate on using finish instead of intent.
-    val intent = Intent(this, ProfileChooserActivity::class.java)
-    intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP)
-    startActivity(intent)
+    finish()
     return false
   }
 

app/src/sharedTest/java/org/oppia/android/app/profile/AddProfileActivityTest.kt

@@ -13,6 +13,7 @@ import androidx.appcompat.app.AppCompatActivity
 import androidx.test.core.app.ActivityScenario.launch
 import androidx.test.core.app.ApplicationProvider
 import androidx.test.espresso.Espresso.onView
+import androidx.test.espresso.action.ViewActions
 import androidx.test.espresso.action.ViewActions.click
 import androidx.test.espresso.action.ViewActions.closeSoftKeyboard
 import androidx.test.espresso.action.ViewActions.pressImeActionButton
@@ -1748,6 +1749,15 @@ class AddProfileActivityTest {
     assertThat(currentScreenName).isEqualTo(ScreenName.ADD_PROFILE_ACTIVITY)
   }
 
+  @Test
+  fun testAddProfileActivity_onBackPressed_finishActivity() {
+    val scenario = launch(AddProfileActivity::class.java)
+    onView(isRoot()).perform(ViewActions.pressBack())
+    testCoroutineDispatchers.runCurrent()
+    scenario.onActivity { activity ->
+      assertThat(activity.isFinishing).isTrue()
+    }
+  }
   private fun createAddProfileActivityIntent(): Intent {
     return AddProfileActivity.createAddProfileActivityIntent(
       ApplicationProvider.getApplicationContext(),