Fix an incorrect auto-correct for Layout/DotPosition

This PR fixes the following incorrect auto-correct for `Layout/DotPosition`
when using only dot line.

```console
% cat example.rb
foo
  .bar
  .
  baz

% rubocop --only Layout/DotPosition -a
(snip)

Inspecting 1 file
C

Offenses:

example.rb:3:3: C: [Corrected] Layout/DotPosition: Place the . on the
next line, together with the method name.
  .
  ^

1 file inspected, 1 offense detected, 1 offense corrected
```

## Before

```consle
% cat example.rb
foo
  .bar

  .baz

% ruby -c example.rb
example.rb:4: syntax error, unexpected '.', expecting end-of-input
  .baz
```

## After

```console
% cat example.rb
foo
  .bar
  .baz

% ruby -c example.rb
Syntax OK
```

changelog/fix_incorrect_autocorrect_for_layout_dot_position.md

@@ -0,0 +1 @@
+* [#9867](https://github.com/rubocop/rubocop/pull/9867): Fix an incorrect auto-correct for `Layout/DotPosition` when using only dot line. ([@koic][])

lib/rubocop/cop/layout/dot_position.rb

@@ -24,6 +24,7 @@ module Layout
       #     method
       class DotPosition < Base
         include ConfigurableEnforcedStyle
+        include RangeHelp
         extend AutoCorrector
 
         def on_send(node)
@@ -42,7 +43,12 @@ def on_send(node)
         private
 
         def autocorrect(corrector, dot, node)
-          corrector.remove(dot)
+          dot_range = if processed_source[dot.line - 1].strip == '.'
+                        range_by_whole_lines(dot, include_final_newline: true)
+                      else
+                        dot
+                      end
+          corrector.remove(dot_range)
           case style
           when :leading
             corrector.insert_before(selector_range(node), dot.source)

spec/rubocop/cop/layout/dot_position_spec.rb

@@ -34,6 +34,22 @@
       RUBY
     end
 
+    it 'registers an offense for only dot line' do
+      expect_offense(<<~RUBY)
+        foo
+          .bar
+          .
+          ^ Place the . on the next line, together with the method name.
+          baz
+      RUBY
+
+      expect_correction(<<~RUBY)
+        foo
+          .bar
+          .baz
+      RUBY
+    end
+
     it 'accepts leading do in multi-line method call' do
       expect_no_offenses(<<~RUBY)
         something