Set retry flag to true by default for OkHttpFactory

[mykola-mokhnach]

Change list

It looks like setting okhttp client to not retry on connection failure by default causes issues while switching contexts (which was previously not the case with apache http client). This PR tries to enforce the default setting to true, but this still requires more testing in the client side, because the problem is not always reproducible.

Types of changes

• No changes in production code.
• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

[iddol]

It would be helpful to make the other private setters and getters (e.g., setResponseCodec(), setCommandCodec() protected as well) - see issue #920.