webkit: Fix file mode for WebViewSandboxTest

No change to logic. This removes the 'x' permission bit from
WebViewSandboxTest.java. This is just a regular file, it doesn't need to be
executable.

Test: N/A
Bug: 266007845
Change-Id: I274e2fc3036b9e3b6a9a9d9f27012c6c4ca13061
1 file changed