Replace Objects.checkFromIndexSize usage with checkBoundOffCount in String

This modifies the patch to be consistent with the rest of the upstream
code.
No behavior change is expected, because the callers in libcore should have
done the bound check.

Bug: 247773125
Test: m droid
Change-Id: Ie56b9605ad409bdc55264a7f174a3691a1a1e054
1 file changed