Revert "eina: change default log level at which we display backtrace."

Revert "eina: change default log level at which we display backtrace."

This reverts commit 05c18876b3e2dba5dd7caea2517aaf24d92ab614.

i endabled backtraces by DEFAULT because it is otherwise pretty damned
hard to get them from things like enlightenment, or on tizen apps as
running them on the cmdline and having them work is close to
impossible. yes it's noise. FIX THE ERRORS then. this commit is just
like turning off gcc etc. warnings because the code is too noisy in
compilation with them on. it's a bug. fix it. the bt lets you do that
without gdb or re-executing AGAIN with an env var and HOPING to find
the bug the next time around.

not to mention efl programming docs cover this backtrace and say it
is on by default and how to get useful info out of this. this makes
the elf docs a lie by removing what is documented as default.

@fix