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/tests/snapshots/format@expression__dict_comp.py.snap

@@ -99,6 +99,22 @@ 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
+}
 ```
 
 ## Output
@@ -251,6 +267,26 @@ selected_choices = {
     k: v
     for (x, aaaayaaaayaaaayaaaayaaaayaaaayaaaayaaaayaaaayaaaayaaaayaaaayaaaayaaaay) in z  # foo
 }
+
+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/tests/snapshots/format@expression__generator_exp.py.snap

@@ -37,6 +37,22 @@ 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
+)
 ```
 
 ## Output
@@ -75,6 +91,26 @@ len(
     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/tests/snapshots/format@expression__list_comp.py.snap

@@ -62,7 +62,24 @@ 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
+]
+```
 
 ## Output
 ```py
@@ -141,6 +158,26 @@ selected_choices = [
     )
     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
+]
 ```