Prefer squiggly heredoc in specs for conflicts

What does this MR do?

Prefer squiggly heredoc in specs for conflicts

This fixes false positives when running overcommit -r.

Now, we no longer need to exclude those specs when checking for conflicts.

Previously, when running overcommit -r we saw:

$ overcommit -r

Running pre-commit hooks

Check for merge conflicts............................[MergeConflicts] FAILED

Merge conflict markers detected:
/home/peter/devel/gitlab/gdk-ee/gitlab/spec/lib/gitlab/conflict/file_spec.rb:162:<<<<<<< files/ruby/regex.rb
/home/peter/devel/gitlab/gdk-ee/gitlab/spec/lib/gitlab/conflict/file_spec.rb:187:<<<<<<< files/ruby/regex.rb
/home/peter/devel/gitlab/gdk-ee/gitlab/spec/lib/gitlab/conflict/file_spec.rb:220:<<<<<<< files/ruby/regex.rb
/home/peter/devel/gitlab/gdk-ee/gitlab/spec/lib/gitlab/git/conflict/parser_spec.rb:22:<<<<<<< files/ruby/regex.rb
/home/peter/devel/gitlab/gdk-ee/gitlab/spec/lib/gitlab/git/conflict/parser_spec.rb:43:<<<<<<< files/ruby/regex.rb
/home/peter/devel/gitlab/gdk-ee/gitlab/spec/lib/gitlab/git/conflict/parser_spec.rb:76:<<<<<<< files/ruby/regex.rb

✗ One or more pre-commit hooks failed

Hide whitespace changes ⭐

This MR indents a lot of code. In order to review it more easily just hide whitespace changes via

or follow the link !24260 (diffs)

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• [-] Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• [-] Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec tea