[lldb] Step through inlined code when stepping out of inline frame N > 0 (#226910)

To step out of an inline frame N > 0, ThreadPlanStepOut first steps out
to frame N, then queues a plan that steps through the inlined block. Due
to a bug, ShouldStop marks the plan complete right after it queues that
plan, so the thread stops as soon as it reaches frame N, with no stop
reason.

In fact, the comment next to that code describes the intended behavior
while implementing something different: only call the StepOut plan done
if the "step out from line" plan cannot be queued.

For example, consider this backtrace:
```
  frame #0: 0x00000001000003c0 deep`sink(x=81) at deep.c:4:6 [opt]
  frame #1: 0x0000000100000418 deep`level3(a=48) at deep.c:11:3 [opt] [inlined]
  frame #2: 0x0000000100000404 deep`level2(b=37) at deep.c:20:3 [opt] [inlined]
  frame #3: 0x00000001000003f0 deep`level1(c=42) at deep.c:28:3 [opt] [inlined]
  frame #4: 0x00000001000003dc deep`main at deep.c:33:3 [opt]
```

This patch changes behavior as follows:

```
command                  before                          after
frame select 1; finish   level3 line 12, no stop reason  level2 line 21, step out
frame select 2; finish   level3 line 12, no stop reason  level1 line 29, step out
```

GitOrigin-RevId: c8344578d8a862527f165c8b348f1e50b6bd25c0