Fix enrolled pages not hide during SUW

Update mIsFaceEnrollable and mIsFingerprintEnrollable in
BiometricEnrollActivity, and use them to determine the activity flow.

Bug: 270102158
Test: Manually test following cases
      1. Complete fp and face in suw, then back to "Google Service" page
	 to make sure
	 a. Fingeprint introduction page isn't shown
	 b. Face introduction page isn't shown
	 c. ConfirmCredential page is shown
      2. Complete fp in suw, then press back to previous page in Face
	 introduction page. And check Fingerpirnt isn't shown.
Change-Id: Ibc74128f6776128d8a0f4cab014b58057ac0f844