Removed or Replaced Broken URLs

[ericspod]

Fixes #8482.

Description

This replaces broken URLs or removes them entirely. Two URLs which are not fixed relate to the RandSmoothDeform images in the DocImages repository, these aren't present so need to be generated later.

Types of changes

• Non-breaking change (fix or new feature that would not break existing functionality).
• Breaking change (fix or new feature that would cause existing functionality to change).
• New tests added to cover the changes.
• Integration tests passed locally by running ./runtests.sh -f -u --net --coverage.
• Quick tests passed locally by running ./runtests.sh --quick --unittests --disttests.
• In-line docstrings updated.
• Documentation updated, tested make html command in the docs/ folder.

[KumoLiu]

Thanks for the fix, LGTM.

[KumoLiu]

/build