Deprecate --browser option from run-tests.sh

Problem/Motivation

As with #2750461: Remove Simpletest UI because we don't want to maintain a graphical test runner, we seek to get rid of the form display elements of run-tests.sh.

If you pass in --browser to run-tests.sh it will show you test results in a web-based form. This is useful because it shows you good information about which test method failed in a PHPUnit test. --verbose does not show you this information, because it truncates that information for tabular display.

Currently, this form also represents a hard dependency between run-test.sh and the simpletest module. This will change in parent issue #3074433: Decouple run-tests.sh from the simpletest module.

Proposed resolution

Deprecate the --browser option in run-tests.sh by triggering a error to the user when they use it.

Either add an option, or modify --verbose to show the entire result output for a test in the CLI.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet