Roll Flutter Engine from 218b71cd7a45 to b5a6b1c9cba5 (1 revision) (#131025)

https://github.com/flutter/engine/compare/218b71cd7a45...b5a6b1c9cba5

2023-07-20 dnfield@google.com [Impeller] [Vulkan] Add reset command buffer bit to command pools. (flutter/engine#43867)

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC bdero@google.com,rmistry@google.com,zra@google.com on the revert to ensure that a human
is aware of the problem.

To file a bug in Flutter: https://github.com/flutter/flutter/issues/new/choose

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

bin/internal/engine.version

-218b71cd7a454d4c5c183f8174f6cbb961744615
+b5a6b1c9cba571c9a77e012a870c53ed67260ff1