Fix bug join operation with non-annotating table

[LucaMarconato]

This PR is very small (I modified only src/spatialdata/_core/query/relational_query.py, the rest is from the new ruff pre-commit).

This PR fixes a subtle bug that originated when all the following occurred simultaneously:

1. we did join operation between an element, and a table that is not annotating the element
2. instead the table is annotating 1 (not 2 or more) other elements
3. the name of the element being annotated is a string that contains the name of the element we are joining against

This occurred for instance with this code:

from spatialdata_io import visium_hd
from pathlib import Path
from napari_spatialdata import Interactive

path = Path("../../spatialdata-sandbox/visium_hd_3.1.1_io")
assert path.exists()

path_read = path / "data"
path_write = path / "data.zarr"

sdata = visium_hd(path_read, load_all_images=True, annotate_table_by_labels=True, bin_size=[16])

interactive = Interactive(sdata, headless=True)
interactive.add_element("Visium_HD_Human_Lung_Cancer_Fixed_Frozen_square_016um", "global")
interactive.run()

This occurred because in the cases above region was a str, not a list[str], and therefore, in the screenshot below,

the check in the highlighted line, which should fail (because the table is not annotating the element), instead succeeds (because name is a substring of regions).
But name is not a valid group of groups_df, which leads to a KeyError.

Solution

The solution is very simple. Still, two observations (CC @melonora):

• we should drop region from the metadata Drop region (region_key and instance_key are enough) #629 and avoid future technical debts, which occurs as this bug showed.
• we should refactor the query APIs, as highlighted here. Problem with indices with left_exclusive join #824 (comment). The current PR exemplify the code redundancy.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.96%. Comparing base (e3ab814) to head (bd24238).
Report is 21 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #864      +/-   ##
==========================================
+ Coverage   91.95%   91.96%   +0.01%     
==========================================
  Files          47       47              
  Lines        7345     7355      +10     
==========================================
+ Hits         6754     6764      +10     
  Misses        591      591              

Files with missing lines	Coverage Δ
src/spatialdata/_core/query/relational_query.py	90.98% <100.00%> (+0.20%)	⬆️

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