[Android] Fix TextInput placeholder multiline

[delphinebugner]

Summary:

On Android, the <TextInput>'s placeholder property always renders to multiple lines, whereas on iOS it trails the ending (like ellipsizeMode="trail").

This PR aligns the Android behaviour to iOS :

• Text Input with multiline=false (default): placeholder uses an ellipsis
• Text Input with multiline=true: placeholder is multiline

More context on:

• Initial issue: TextInput placeholder is always multiline on Android #29663
• Implem inspired by Set ReactTextInput's placeholder ellipsize mode #29664

Changelog:

Test Plan:

• no multiline + long placeholder
• no multiline + short placeholder
• multiline + long placeholder
• multiline + short placeholder
• no placeholder
• when multiline changes in a re-render -> placeholder adapts (see this video : https://github.com/user-attachments/assets/7b77253f-c2ed-4ccf-a1c9-7d3eb9458464)

Showcase

What	Android	iOS (iso)
no multiline + long placeholder	fixed
multiline + long placeholder	iso before