Tweak breaking groups for comprehensions (#6321)

## Summary

Fixes some comprehension formatting by avoiding creating the group for
the comprehension itself (so that if it breaks, all parts break on their
own lines, e.g. the `for` and the `if` clauses).

Closes https://github.com/astral-sh/ruff/issues/6063.

## Test Plan

Bunch of new fixtures.

crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/dict_comp.py

@@ -93,3 +93,19 @@ selected_choices = {
 
     x, aaaayaaaayaaaayaaaayaaaayaaaayaaaayaaaayaaaayaaaayaaaayaaaayaaaayaaaay) in z
 }
+
+a = {
+    k: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+    for f in bbbbbbbbbbbbbbb
+    if f not in ccccccccccc
+}
+
+a = {
+    k: [1, 2, 3,]
+    for f in bbbbbbbbbbbbbbb
+    if f not in ccccccccccc
+}
+
+aaaaaaaaaaaaaaaaaaaaa = {
+    k: o for o in self.registry.values if o.__class__ is not ModelAdmin
+}

crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/generator_exp.py

@@ -31,3 +31,19 @@ len(
     a for b in c
     # trailing
 )
+
+a = (
+    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+    for f in bbbbbbbbbbbbbbb
+    if f not in ccccccccccc
+)
+
+a = (
+    [1, 2, 3,]
+    for f in bbbbbbbbbbbbbbb
+    if f not in ccccccccccc
+)
+
+aaaaaaaaaaaaaaaaaaaaa = (
+    o for o in self.registry.values if o.__class__ is not ModelAdmin
+)

crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/list_comp.py

@@ -56,4 +56,20 @@ selected_choices = [
 
 # Tuples with BinOp
 [i for i in (aaaaaaaaaaaaaaaaaaaaaa + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb, ccccccccccccccccccccc)]
-[(aaaaaaaaaaaaaaaaaaaaaa + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb, ccccccccccccccccccccc) for i in b]
+[(aaaaaaaaaaaaaaaaaaaaaa + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb, ccccccccccccccccccccc) for i in b]
+
+a = [
+    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+    for f in bbbbbbbbbbbbbbb
+    if f not in ccccccccccc
+]
+
+a = [
+    [1, 2, 3,]
+    for f in bbbbbbbbbbbbbbb
+    if f not in ccccccccccc
+]
+
+aaaaaaaaaaaaaaaaaaaaa = [
+    o for o in self.registry.values if o.__class__ is not ModelAdmin
+]