[entity] more tweaks for entity attribute cache handling on cw_set/cw_create to fix test regression
* when an attribute is listed in dont-cache-attrs, purge any previous value
* test value is actually modified in EditedEntity.__setitem__ before adding
attribute to dont-cache-attrs
option_group_changed('port', 'main', 'web')
option_group_changed('query-log-file', 'main', 'web')
option_group_changed('profile', 'main', 'web')
option_group_changed('max-post-length', 'main', 'web')