[DocsUI Peek] GlideAppModule - set memory cache size

The Glide configuration is shared across DocumentsUI, since
Glide could potentially be used in the future outside of Peek
(e.g. thumbnail loading/caching).

Bug: 382170389
Flag: com.android.documentsui.flags.use_material3
Flag: com.android.documentsui.flags.use_peek_preview_ro
Test: PeekUiTest still pass
Change-Id: Icb2b8f72cd72c47f73c1a33a48187cfae7a6c9d1