improve a ConcretizationTypeError message from dependence on jitted function arguments

[mattjj]

Previously, given this function:

import jax

@jax.jit
def f(x,y):
  if x > y:
    return x
  else:
    return y

we'd get an error message like this (after #4038, improved to help with omnistaging debugging):

...

While tracing the function f at tim.py:3, this value became a tracer due to JAX operations on these lines:

  operation c:bool[] = gt a:int32[] b:int32[]
    from line tim.py:5 (f)

...

But this message is buggy! In this case, the value is a tracer because it has a data dependence on arguments to a jitted function.

After this change, we instead produce this error message:

...

While tracing the function f at tim.py:3, this concrete value was not available
in Python because it depends on the value of the arguments to f at tim.py:3
at positions [0, 1], and the computation of these values is being staged out.

...

I'm eager to iterate with further improvements, but for now I want to fix this buggy message.