[lldb][test] Fix ThreadStepUntilAPI.py
After #167359 / 95db31e7f69e7008f0c570ed30d54d1e418e10f2.
A fix was attempted in #167423 but was not quite enough.
From what I could understand, in v1 format you have to specify
all the basic blocks. Where before !call_me implied they were all
cold (I think, very shaky understanding here).
For this test we want to see blocks like call_me/foo/call_me.
So adding a line for block 1 fixes the tests.
It could produce more blocks at some point but I think as long
as foo is within two of them, it'll be fine.
