follow up: enable auto quorum set configuration by default after v22.3.0 release

[bboston7]

#270 added an option to skip validator checks for testing purposes. This change relies on a new stellar-core option that isn't yet available in stable images. As a result, we incorporated two pieces of functionality to accommodate old stellar-core versions:

1. Tests that use the oldImage option fall back on manual quorum set configuration
2. The option --enable-relaxed-auto-qset-config is required to enable the new stellar-core option.

Once the option has filtered down to the stable image, we should:

1. Use auto quorum set configuration where possible on oldImages.
2. Remove the --enable-relaxed-auto-qset-config option, or enable it by default.