Revert pandas-dev#24048 change that caused bug.

Write tests first

When tested with a variable that has the wrong dtype, this raises an
exception instead of False

When supplied a variable with the wrong type get_loc should raise a
KeyError (not type error). Otherwise things like checking if a variable
is in an index will fail.

This is enough for making the test pass but it's not the right implementation

Include some non-monotonic/overlapping IntervalIndex.
This triggers another bug, due to the fact that self.get_loc(i)
is called on an unexpected key.

Move the test from indexing/test_loc to index/interval/test_interval.

target was missing from call to _find_non_overlapping_monotonic_bounds

Instead of returning [-1, -1, -1] when the middle value is incorrect
type, return [a, -1, b].

Add mix of invalid and valid values

Fixes test_with_overlaps test

interval.get_indexer() should still raise a TypeError in cases
where the types are unorderable. This is needed for DataFrame.append
for example, which was breaking tests in test_concat.