**What and why**
This PR fixes a memory leak in the `Canvas.drawVertices` JNI
implementation. The `indexArr` elements were accessed via
`GetShortArrayElements` but were never released, which could lead to
pinned arrays or memory exhaustion over time.

**Testing**
Successfully built the native C++ libraries locally on Windows x64. Ran
tests — all passed except `TextLineTest.emojiTest`, which seems to be a
local Windows environment issue unrelated to Canvas bindings.

**Release Notes**
* Fixed a JNI memory leak in `Canvas.drawVertices`.

**Issue:**

https://youtrack.jetbrains.com/issue/SKIKO-1149/Memory-leak-pinned-array-in-Canvas.drawVertices-JNI-due-to-missing-ReleaseShortArrayElements