CRM-12273 minor QA for some DB state observed after upgrade after checki...

After checking the PR 323 found the DB state after upgrade :  
  -  price set for memebership block of membership contribution page was not getting created.
  -  also contributions with only other amount, dont get the price_field_id of 'other amount' price set instead get default amount price set's price_field_id.

this PR solves the bug as well as the above mentioned points.