Avoid leaking RenderEngine

... as this might allow an underlying `RenderEngineThreaded` thread
to race.

Bug: b/368983946
Test: stress test of VtsHalGraphicsComposer3_TargetTest
Bug: b/361574971
Test: ATP cuttlefish_gfxstream_guest_angle_graphics_vts_tests
(cherry picked from https://android-review.googlesource.com/q/commit:64f73a4c5fdc79a882c9047e69d9f64b89c013b9)
Merged-In: Ief71d8931ec3560780a850d8bb8bc727bbff5c52
Change-Id: Ief71d8931ec3560780a850d8bb8bc727bbff5c52