bluetooth: fast_pair: Delete "reset" flag instead of storing false

Change deletes Fast Pair storage manager's "reset" flag instead of
storing it as false to ensure no data is left in settings after a
successful factory reset operation.

Jira: NCSDK-20219

Signed-off-by: Marek Pieta <Marek.Pieta@nordicsemi.no>

doc/nrf/releases_and_maturity/releases/release-notes-changelog.rst

@@ -347,6 +347,11 @@ Binary libraries
 Bluetooth libraries and services
 --------------------------------
 
+* :ref:`bt_fast_pair_readme` library:
+
+  * Deleted reset in progress flag from settings storage instead of storing it as ``false`` on factory reset operation.
+    This is done to ensure that no Fast Pair data is left in the settings storage after the factory reset.
+
 * :ref:`bt_mesh` library:
 
   * Added:

subsys/bluetooth/services/fast_pair/fp_storage/fp_storage_manager.c

@@ -76,8 +76,13 @@ static int reset_in_progress_set(bool in_progress)
 {
 	int err;
 
-	err = settings_save_one(SETTINGS_RESET_IN_PROGRESS_FULL_NAME, &in_progress,
-				sizeof(in_progress));
+	if (in_progress) {
+		err = settings_save_one(SETTINGS_RESET_IN_PROGRESS_FULL_NAME, &in_progress,
+					sizeof(in_progress));
+	} else {
+		err = settings_delete(SETTINGS_RESET_IN_PROGRESS_FULL_NAME);
+	}
+
 	if (err) {
 		return err;
 	}