fix(tests): revert test-breaking changes of e5c7ae4

The commit e5c7ae4 seemed to (potentially erronously?) remove a number of
spaces following the left `|` bar of some graphical report handler tests.
That change had no effect on the `syntax_highlighter_on_real_file()`
test, presumably because the trailing whitespace is removed by
`strip_ansi_escapes::strip_str()`, but it did break the
`triple_adjacent_highlight()` and `non_adjacent_hightlight()` tests.
Restoring the spaces removed in e5c7ae4 fixes the failing tests on main.

tests/graphical.rs

@@ -1864,11 +1864,11 @@ fn syntax_highlighter_on_real_file() {
     let expected = format!(
         r#"  × This is an error
       ╭─[{filename}:{l2}:{CO}]
- {l1} │
+ {l1} │ 
  {l2} │     let (filename, line) = (file!(), line!() as usize);
       ·                            ─────────────┬─────────────
       ·                                         ╰── this is a label
- {l3} │
+ {l3} │ 
       ╰────
 "#,
         l1 = line - 1,
@@ -1911,13 +1911,13 @@ fn triple_adjacent_highlight() -> Result<(), MietteError> {
  1 │ source
    · ───┬──
    ·    ╰── this bit here
- 2 │
- 3 │
+ 2 │ 
+ 3 │ 
  4 │   text
    ·   ──┬─
    ·     ╰── also this bit
- 5 │
- 6 │
+ 5 │ 
+ 6 │ 
  7 │     here
    ·     ──┬─
    ·       ╰── finally we got
@@ -1957,10 +1957,10 @@ fn non_adjacent_highlight() -> Result<(), MietteError> {
  1 │ source
    · ───┬──
    ·    ╰── this bit here
- 2 │
+ 2 │ 
    ╰────
    ╭─[bad_file.rs:5:3]
- 4 │
+ 4 │ 
  5 │   text    here
    ·   ──┬─
    ·     ╰── also this bit