[clang-format] AlignConsecutiveAssignments breaks at multiline trailing block comments

Input (expected stable):
```
struct M {
int d = 1; /* d */
int abcd = 2; /* abcd
test */
int e = 1;
};
```
Actual output (`int e` loses alignment):
```
struct M {
int d = 1; /* d */
int abcd = 2; /* abcd
test */
int e = 1;
};
```
.clang-format settings:
```
BasedOnStyle: LLVM
AlignConsecutiveAssignments: true
ColumnLimit: 0
```
The multiline trailing block comment breaks the consecutive assignment alignment sequence, so `int e` is not aligned with `int d` and `int abcd` above it.

Discovered while working on #208324.

Start with the clang-format reproducer and the shown AlignConsecutiveAssignments settings, then trace how a multiline trailing block comment affects the consecutive assignment sequence. Add a regression test covering the example and verify that the final assignment remains aligned with the preceding assignments.

Written by the indexing model from the issue text.