EGL BlobCache: Check properties on use

This ensures we don't incur a system property lookup
hit for apps that don't end up using the cache.

Test: Boot (quickly)
Test: pubg_mobile_launch ANGLE trace
Test: /data/nativetest64/EGL_test/EGL_test
Test: /data/nativetest64/libEGL_test/libEGL_test
Bug: b/266725576
Change-Id: Ia69b8d48a5902921bea7faad0b2fad6dc1ed7d0c