[sb] set maxLines to 1 for the battery estimate

The bug: longer-ish battery remaining estimates can cause the text
composable to wrap onto the second line. We don't want that.

The fix: don't let it do that

Test: manual; set font size / display size to largest when the estimate
would have wrapped. Verify that it doesn't wrap.
Fixes: 409157513
Flag: com.android.settingslib.flags.new_status_bar_icons

Change-Id: I04ed28836ec4dd220553c70f7788083f551954f4