Previously, disabling SecurityAutoConfiguration could cause
SecurityFilterAutoConfiguration to fail if Spring Security’s filter
chain bean existing in the context. SecurityFilterAutoConfiguration
relies on SecurityProperties which is created by
SecurityAutoConfiguration. When SecurityAutoConfiguration is disabled,
there’s no SecurityProperties bean so SecurityFilterAutoConfiguration
would fail due to the missing dependency.

This commit updates SecurityFilterAutoConfiguration to create a
SecurityProperties bean if one does not already exist.

Closes gh-4525