Settings: Start search result deep link in same task

This fixes a bug where the deep link initiated from a search result
would open the results page in a separate window. The root cause was the
inclusion of the FLAG_ACTIVITY_NEW_TASK intent flag.

Bug: 381127948
Test: atest SettingsSpaUnitTests:com.android.settings.activityembedding
Test: atest CtsSettingsTestCases:SettingsMultiPaneDeepLinkTest
Test: Manually verify UI
Flag: com.android.settings.flags.settings_search_result_deep_link_in_same_task
Change-Id: I91f9e5096ad02bd87e43bae03a2b3e69256be651