Remove fallback that assigns a module to inlined frames. (#51405)
The work I did in #41099 introduced code which, if method information
could not be found for an inlined frame, would fall back to use the
module of the next-higher stack frame. This often worked there because
the only frames that would not be assigned a module at this point would
be e.g., `macro expansion` frames.
However, due to the performance impact of the way method roots are
currently encoded, the extra method roots were removed in #50546.
The result is that inlined frames were being assigned a potentially
incorrect module, rather than being left blank.
Example:
```
julia> @btime plot([1 2 3], seriestype = :blah)
...
[13] #invokelatest#2
@ BenchmarkTools ./essentials.jl:901 [inlined]
[14] invokelatest
@ BenchmarkTools ./essentials.jl:896 [inlined]
...
```
