[lldb/testsuite] Tweak TestBreakpointLocations.py to pass for arm64

The test checks that we correctly set the right number of breakpoints
when breaking into an `always_inline` function. The line of this
funstion selected for this test was the return statement, but with
recent compiler, this return statement doesn't necessarily exist after
inlining, even at O0.

Switch the breakpoint to a different line of the inline function.