Reduce misleading test failures caused by HTTP timeouts

[SergeyBiryukov]

A number of HTTP external tests can randomly fail due to timeouts.

[34848] improved things a bit, however it only uses ::skipTestOnTimeout() in three tests, whereas there's a lot more tests with similar random timeouts from time to time.

Seems like ::skipTestOnTimeout() should be used in any HTTP test that can fail due to a timeout.

Another option is to only run these tests when HTTP-related changes were made.

[SergeyBiryukov]

In 43511:

Tests: Use WP_HTTP_UnitTestCase::skipTestOnTimeout() in more HTTP tests.

Adjust it to handle more types of timeouts, e.g. "Resolving timed out", "Connection timed out".

See #44613.

[SergeyBiryukov]

In 43512:

Tests: Introduce Tests_HTTP_Functions::skipTestOnTimeout(), mirroring the same WP_HTTP_UnitTestCase method.

See #44613.

[SergeyBiryukov]

In 43625:

Tests: Use WP_HTTP_UnitTestCase::skipTestOnTimeout() in more HTTP tests.

Adjust it to handle more types of timeouts, e.g. "Resolving timed out", "Connection timed out".

Merges [43511] to the 4.9 branch.
See #44613.

[SergeyBiryukov]

In 43626:

Tests: Introduce Tests_HTTP_Functions::skipTestOnTimeout(), mirroring the same WP_HTTP_UnitTestCase method.

Merges [43512] to the 4.9 branch.
Fixes #44613.

[pento]

This can be merged into the 5.0 branch.

[SergeyBiryukov]

In 43695:

Tests: Use WP_HTTP_UnitTestCase::skipTestOnTimeout() in more HTTP tests.

Adjust it to handle more types of timeouts, e.g. "Resolving timed out", "Connection timed out".

Merges [43511] to the 5.0 branch.
See #44613.

[SergeyBiryukov]

In 43696:

Tests: Introduce Tests_HTTP_Functions::skipTestOnTimeout(), mirroring the same WP_HTTP_UnitTestCase method.

Merges [43512] to the 5.0 branch.
Fixes #44613.

[SergeyBiryukov]

In 46682:

Tests: Skip test_readme() if the HTTP request to secure.php.net or dev.mysql.com failed on timeout.

Move skipTestOnTimeout() to WP_UnitTestCase_Base to avoid duplication.

See #44613.

[SergeyBiryukov]

In 46996:

Tests: In test_readme(), if the HTTP request to secure.php.net or dev.mysql.com failed, include response code in the error message.

See #40533, #44613.