Preserve newlines after nested compound statements (#7608)

## Summary

Given:
```python
if True:
    if True:
        pass
    else:
        pass
        # a

        # b
        # c

else:
    pass
```

We want to preserve the newline after the `# c` (before the `else`).
However, the `last_node` ends at the `pass`, and the comments are
trailing comments on the `pass`, not trailing comments on the
`last_node` (the `if`). As such, when counting the trailing newlines on
the outer `if`, we abort as soon as we see the comment (`# a`).

This PR changes the logic to skip _all_ comments (even those with
newlines between them). This is safe as we know that there are no
"leading" comments on the `else`, so there's no risk of skipping those
accidentally.

Closes https://github.com/astral-sh/ruff/issues/7602.

## Test Plan

No change in compatibility.

Before:

| project | similarity index | total files | changed files |

|--------------|------------------:|------------------:|------------------:|
| cpython | 0.76083 | 1789 | 1631 |
| django | 0.99983 | 2760 | 36 |
| transformers | 0.99963 | 2587 | 319 |
| twine | 1.00000 | 33 | 0 |
| typeshed | 0.99979 | 3496 | 22 |
| warehouse | 0.99967 | 648 | 15 |
| zulip | 0.99972 | 1437 | 21 |

After:

| project | similarity index | total files | changed files |

|--------------|------------------:|------------------:|------------------:|
| cpython | 0.76083 | 1789 | 1631 |
| django | 0.99983 | 2760 | 36 |
| transformers | 0.99963 | 2587 | 319 |
| twine | 1.00000 | 33 | 0 |
| typeshed | 0.99983 | 3496 | 18 |
| warehouse | 0.99967 | 648 | 15 |
| zulip | 0.99972 | 1437 | 21 |

crates/ruff_python_formatter/tests/snapshots/format@statement__if.py.snap

@@ -213,6 +213,31 @@ if True:
 else:
     pass
 
+if True:
+    if True:
+        pass
+    else:
+        pass
+        # a
+
+        # b
+        # c
+
+else:
+    pass
+
+if True:
+    if True:
+        pass
+    else:
+        pass
+
+        # b
+        # c
+
+else:
+    pass
+
 
 # Regression test for: https://github.com/astral-sh/ruff/issues/7602
 if True:
@@ -493,6 +518,31 @@ if True:
 else:
     pass
 
+if True:
+    if True:
+        pass
+    else:
+        pass
+        # a
+
+        # b
+        # c
+
+else:
+    pass
+
+if True:
+    if True:
+        pass
+    else:
+        pass
+
+        # b
+        # c
+
+else:
+    pass
+
 
 # Regression test for: https://github.com/astral-sh/ruff/issues/7602
 if True:
@@ -503,7 +553,6 @@ if True:
         # a
         # b
         # c
-
 else:
     pass
 
@@ -515,6 +564,7 @@ if True:
 
         # a
         # c
+
 else:
     pass
 
@@ -528,7 +578,6 @@ if True:
         # a
         # b
         # c
-
 else:
     pass
 

crates/ruff_python_formatter/tests/snapshots/format@statement__import.py.snap

@@ -71,6 +71,17 @@ import os
 
 
 logger = logging.getLogger("FastProject")
+
+# Regression test for: https://github.com/astral-sh/ruff/issues/7604
+import os
+# comment
+
+# comment
+
+
+# comment
+x = 1
+
 ```
 
 ## Output
@@ -149,6 +160,16 @@ import os
 
 
 logger = logging.getLogger("FastProject")
+
+# Regression test for: https://github.com/astral-sh/ruff/issues/7604
+import os
+# comment
+
+# comment
+
+
+# comment
+x = 1
 ```