Update Test913 to check for .art] to detect if there's an image

Test913 checks if Object.class is in image space when an image is
loaded. The test checks for a ".art" mapping in /proc/self/maps to
check if an image exists. We should also check for ".art]".

Bug: 318039063
Test: art/test.py -t 913
(cherry picked from https://android-review.googlesource.com/q/commit:9a3ca371e9fe14ccf4e55fd1c9a8c45b01b5250c)
Merged-In: I0ef5ae0dc35669dd5603b35e34f00e653f70a3c1
Change-Id: I0ef5ae0dc35669dd5603b35e34f00e653f70a3c1