Fix disruptive announcement on PIN/Password set up

- Do not invoke deprecated announceForAccessibility()
- Define corresponding content description for PIN & Password

Flag: EXEMPT for a11y bug fixinig
Bug: 384607370
Test: Enabled Talkback, Setup Screen Lock PIN/Password,
ensure the "Password is now set up" for set up password, and
the "PIN is now set up" announced without disruptive announcement

Change-Id: I97c2c7fd8824468fccca8526c4e61ce642fd62ac