[webapi]Delete duplicate tests in CSS Backgrounds tests xml

- Remove 1 duplicate test in tests.xml
- Remove 33 deulicate test in tests.full.xml
Merge pull request #1212 from chenxix/chenxi/misc-uiautomation/delete-duplicate-case

[webapi]Delete duplicate tests in CSS Background tests xml
[stability]Add exit 0

[Detailed commit message (if have)]
Impacted TCs num(approved): New 0,Update 3
Unit test platform: [Tizen]
Test Result:Pass 5, fail 0, block 0
Merge pull request #1213 from linshen/shenlin/update-sh-exit0

[stability]Add exit 0