Cleanup src/test_utils

[mshustov]

Working on #76082 I found that src/test_utils is outdated and has a dependency on data plugin. We need to clean up the project and remove the dependency on plugins.

• https://github.com/elastic/kibana/blob/master/src/test_utils/get_url.js used in 2 functional tests, might be moved to a @kbn/test

Move to data plugin (fix #78518)

• https://github.com/elastic/kibana/blob/master/src/test_utils/public/stub_index_pattern.js

Not used (removed in #76528)

• https://github.com/elastic/kibana/blob/master/src/test_utils/public/static_html_id_generator.js
• https://github.com/elastic/kibana/blob/master/src/test_utils/expect_deep_equal.js
• https://github.com/elastic/kibana/blob/master/src/test_utils/public/simulate_keys.js
• https://github.com/elastic/kibana/blob/master/src/test_utils/public/ng_mock.js
• https://github.com/elastic/kibana/blob/master/src/test_utils/public/image_comparator.js
• https://github.com/elastic/kibana/blob/master/src/test_utils/public/mocks/intl.js

All the remaining code should be converted into TypeScript.

[mshustov]

@lukeelmers I noticed you added this comment https://github.com/elastic/kibana/blob/master/src/test_utils/public/stub_index_pattern.js#L21-L23 in #42994
what is your plan regarding the stub?

[lukeelmers]

@restrry Sorry I missed this comment earlier. The plan was to replace this with a new/updated stub in the data plugin since there isn't really a need for this to live in test_utils, but it looks like we missed it in the migration process. I will try to make a PR for moving this in the next couple of days.

[lukeelmers]

PR moving StubIndexPattern to the data plugin is here: #78518