Reasses dims without coords

[ricardoV94]

Description

It is currently possible to create dims without coords via pm.Data:

import pymc as pm

with pm.Model() as m:
  x = pm.MutableData("x", [0, 1, 2], dims=("dim_without_coord",))
  y = pm.Normal("y", x.sum(), dims=("dim_without_coord",))

We used to allow this also from RVs in the past but reverted in #6112
I don't see a fundamental difference between the two cases, and in that PR I just missed this.

I would suggest we remove this functionality because it adds quite some complexity in the Model class, including fancy checks to see if a Data variable defined from dims without coords of another Data variable is being resized before the original one (but after is fine?):

pymc/tests/model/test_core.py

Lines 923 to 937 in 02cbac6

	def test_set_data_warns_on_resize_of_dims_defined_by_other_mutabledata():
	with pm.Model() as pmodel:
	pm.MutableData("m1", [1, 2], dims="mutable")
	pm.MutableData("m2", [3, 4], dims="mutable")
	# Resizing the non-defining variable first gives a warning
	with pytest.warns(ShapeWarning, match="by another variable"):
	pmodel.set_data("m2", [4, 5, 6])
	pmodel.set_data("m1", [1, 2, 3])
	# Resizing the definint variable first is silent
	with warnings.catch_warnings():
	warnings.simplefilter("error")
	pmodel.set_data("m1", [1, 2])
	pmodel.set_data("m2", [3, 4])

(The unawareness) of this option has also led to bugs that were only patched recently: #6882

[ricardoV94]

This led to another bug in #7376